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We Need New Motherboards Before GPUs Collapse Under Their Own Gravity


This is not a new problem, back in the late 80s I worked for a Mac graphics card developer ... We made some of the first 24bit accelerated graphics cards.

Our first was just an existing card with a small daughter card with pals an sram on it, it was so easy that we got our own logos put on many of the chips to put the competition off the scent, we designed that one in days and got it to market in weeks.

We immediately started on 2 more designs. The next was all FPGA, it was as big a nubus card as one could build, it pulled too much power, and tilted under it's own weight out of the bus socket (Mac's didn't use screws to hold cards in place, that happened when you closed the chassis). We got it out the door about the point that the competition beat the first board's performance.

The final card was built with custom silicon, designed backwards from "how fast can we possibly make the vrams go if we use all the tricks?", In this case we essentially bet the company on whether a new ~200 pin plastic packaging technology was viable. This design really soaked the competition.

In those days big monitors didn't work on just any card so if you owned the high end graphics card biz you owned the high end monitor biz too ... The 3 card play above was worth more than $120m


I may well have used those cards for work! Radius, RasterOps or SuperMac?


SuperMac - the first one was the "SuperMac Spectrum/24 series III", I can't remember the name of the big FPGA thing

I built the accelerator on the last project (that 200 pin chip - look for a chip SQD-01 aka 'SQuiD') that was the basis of a whole family of subsequent cards (starting with the Thunder cards)


I loved those cards. My daily driver was a fully stacked IIfx with a SuperMac card. I remember telling my friends my display was more than a thousand pixels (1152 or something) wide.


I have a SuperMac Thunder/24 w/ DSP upgrade currently in a Quadra 840AV in my little home office museum here. I even have the original boxes, software, etc. :-)

I'm a fan of your work! I'd love to chat sometime.


I’d love to know more about that, if you blog or podcast, please share us a link.

I never owned one of those cards but worked on a Mac that did on a summer job as a teen.


I was going to guess TARGA, but maybe those cards were PC only?


I remember back then searching ebay for a used Targa, but being confused by why all of the result thumbnails were Porsches.


This might be a weird question, but do you have any rundowns of the architecture handy?

I love Retrocomputing and it sounds like an awesome thing to look at.


Nothing in particular - VRAM was the core of all the cards thise days, the serial port shift register (inside the VRAM) fed muxes that in turn fed luts and out to the display.

The VRAM array was 2 sets of 96 bits wide - the accelerator was in part a 1:4 24:96 mux that drove the VRAM array - that's how the dumb frame buffer worked.

I'd spent a year before all this writing code to grab stats figure out where the mac graphics code spent it's time, initially we'd expected to optimise drawing vectors (ie lines - autocad was driving the parallel PC graphics market at the time) - my big discovery was that for the sorts of workloads that our customers were using 99% consisted of just 4 operations:

- solid fills (>90%) - patterned fills - copying within the FB (ie scrolling) - writing text (quite low by important for the DTP market)

I wrote the spec for the first 2 cards (to do the first 3 operations) and the went off to design the 3rd chip (modelled in C, turned into an inch thick spec describing the state machines and data paths and then passed to someone else to make gates)

I added a hack on top of the copy primitive to accelerate text hiliting.

So that accelerator chip also contained a state machine did 4 simple things as fast as it possibly could (solid fills used magic modes in the VRAMS, it could fill at 1.5Gbytes/sec - faster than the high end 3D hardware at the time)

In the end the text fill was useful, but not that much faster (it turned 1-bit font images into 24-bit pixels on the fly), all that cool hardware was pissed away by the way the underlying apps used the font rendering subsystem (page maker invalidated the font cache every line, quark did an N-squared thing, etc)


my big discovery was that for the sorts of workloads that our customers were using 99% consisted of just 4 operations

Those are the same operations that most if not all of even the very cheapest "2D-only" integrated graphics are capable of, starting from the early 90s up to today.


I'm surprised this isn't mentioned here more clearly: Some high end cases like the be quiet silent base I'm using have the option to mount the graphics card vertically, basically parallel to the mainboard, in a separate anchor slot. It needs an additional connector cable (~$20), but other than that is easy to setup, looks better with a look-in case (the illuminated fans face the glass side) and the weight pulls on a special anchor point just for that with no electronics involved. Plus the card itself is more sturdy in that orientation and there is no issues with bending through its own weight. It might even be beneficial ventilation-wise as the graphics card no longer causes a horizontal divide (basically creating separate ventilation-zones on the top and bottom of the card).

Yes, the cable will add approximately ~0.3ns of additional latency due to the added 10cm of distance.

This is how it looks like:


These 4-slot cards won't fit in most vertical mounts, and if they do the fans might be pressed up against the side panel. But that's definitely a good route to go, now that case manufacturers know what they're dealing with.


Or simply use a case which has the ports at the top, so both motherboard and graphics card are vertically oriented, but still plugged in normally. Case fans are at the bottom and push air up out the back slots at the top.

Example: Silver Stone Fortress case


I like my mini-ITX case (Phanteks Shift Air 2) because it hangs the GPU from the top and it's sitting behind a mesh so it still has ample access to fresh air.


I'm getting a Cloudflare error page on that link: 'The owner of this website does not allow hotlinking to that resource'


Huh, didn't realise it spits out that kind of an error. I guess Cloudflare whitelists your IP address if you visit it once since that links still works for me without visiting the original URL?

Anyways, you can see the photo here:


I could open the link in a private/incognito window.


Wow, this is almost exactly as I wanted (except I wanted a horizontal mount akin to blade servers). Never seen it, thanks.


This is a helpful post because I have exactly that case and no idea what that slot was for!

It's a fantastic case.


I was going to say much the same. Vertical mount is a game changer.

Whilst this example is a bit on the extreme side:

It does have some nice properties, no GFX card sag, any water cooling leaks can't drop on expensive components, power supply is back and away too.

Most important point is the cables out the top are covered by a shield so you don't have the ugliness.


How does latency impact rendering etc?


PCI latency has no impact on rendering, but your card/motherboard may fallback to PCIE3 instead of using PCIE4, in which case filling the cards entire VRAM from RAM could take an extra half-second (slowing the loading of new textures an infinitesimal amount).


Modern engines also do a lot of streaming data to VRAM, rather than loading everything up front. So it’s not necessarily a single delay and could very well impact framerates etc.


Every time I see the sizes of GPUs increase, I'm reminded of this from over 2 decades ago:


The fact that even the “not to be sold in china” bit is so on point even today is kind of scary


Or it is relaxing to be reminded, that all those geopolitical tensions and struggles are basically nothing new, so should not be taken too seriously.


Haha: "Bitchin'fast!3D²⁰⁰⁰ supports neither OpenGL nor Direct3D, nor does it fit in any case known to man."

Almost like some giant graphics cards...


The sgi onyx reality engine "graphics card" was composed of like 5 motherboard sized pcb's.


I think it was 3 to 6 VME-sized boards. There was 1 Display Generator board, 1 Geometry Engine board (12 x Intel i860 processors in the RealityEngine2), and 1, 2, or 4 Raster Manager boards (for framebuffer and texture memory). I’m not sure if the maximum configuration of 6 boards could fit in the deskside chassis. That might have required the full rack chassis which had space for several sets of cards for multi-pipe systems. As for cooling, I know the full rack chassis had a huge blower. I’m not sure if the deskside models had blowers or more traditional axial fans.


415 Bungholiomarks ought to be good enough for anyone.


This has to have been before every graphic card advertisement included a 3D rendering a scanty-clad heroine.


Here is a video review of the BitchingFast 3D 2000:


The same Youtuber did a 4090 "review" for April fool day


"256 MB of curiously high bandwidth"


If you watch the linked YouTube video, one of the card's marketing materials — which clearly exactly 0 people read prior to publication — is quoted (screenshotted, in the video[1]) as,

> has a total length of 2704mm and a surface area of 905637mm²

We're going to need a bigger case.



Looks like not only won't it fit to any case, it may even have some problems fitting in some smaller home offices as well. But hey, it doesn't need a support bracket!


> Should we have GPU VRAM slots alongside CPU RAM slots? Is that even possible?

I chuckled a little at this because I used to wonder the same thing until I had to actually bring up a GDDR6 interface. Basically the reason GDDR6 is able to run so much faster is because we assume that everything is soldered down, and not socketed/slotted.

Back when I worked for a GPU company, I occasionally had conversations with co-workers about how ridiculous it was that we put a giant heavy heatsink CPU, and a low profile cooler on the GPU, which in today's day and age produces way more heat! I'm of the opinion that we make mini ATX shaped graphics cards so that you bolt them behind your motherboard (though you would need a different case that had standoffs in both directions.)


I had the misfortune of bringing up firmware for an overengineered piece of crap with DDR5 and even though we had the proper measuring equipment instrumenting properly is barely possible. It's designed with reflections in mind and there's a loopback channel at a slower word rate that I think the controller uses to characterize the analog signal because it's like, barely digital.


Did Synopsys design the DDR5 controller by any chance?


I don't remember but I think no, it was a Renenas chip? I think?


The NUC Extreme line is basically that, which IMO is a really good form factor.

Memory and nvme storage are dense enough to make anything larger obsolete for the practical needs of most users. Emphasis on ‘practical’, not strictly ‘affordable’.

The only advantages of larger form factors are the ability to add cheaper storage, additional PCI-e cards, and aftermarket cosmetic changes such as lighting. IMO, each of these needs represent specialist use cases.


Pretty much, but I'd change the dimensions of the graphics card to match mini ITX, and so that it could be bolted to the case. This provides two benefits: It can support a bigger and heavier heatsink and it also allows you to spread the VRMs around the chip and DRAMs for more consistent power flow.


Okay, how about this: The PCI slot goes on the bottom of the mini-ITX motherboard, and extends out of the bottom of the case. The GPU is in its own enclosure, with a PCI edge connector on the top, and you stack one on top of the other.

I'd really like to find a way to daisy-chain them, but I know that's not how multi-gigabit interfaces work.

Raspberry Pi hats are cool. Why not big mini ITX hats? Yes, I just want to go back to the time of the Famicom Disk System, the Sega CD or the Satellaview.


> The NUC Extreme line is basically that, which IMO is a really good form factor.

Missed that one. I still mourn BTX.


I wish a PC form factor like NLX[0] had become popular where the CPU and memory is on a board that's inserted into a backplane parallel to the add-in cards (similar to VME[1]). IIRC NLX was mostly intended for low-profile applications like corporate desktops and retail systems (point-of-sales) but it never caught on. I can see the edge connector and backplane potentially being an issue with old school parallel PCI (that's a lot of pins) but the serial nature of modern PCIe and the advent of PCIe switches would significantly reduce the number of signal lines.




> The NUC Extreme line is basically that, which IMO is a really good form factor.

Is there a case like this, but that is not part of a prebuild computer?


I have been thinking about picking up this miniITX, Cooler Master NR200P[0]. Similar form factor that would be completely adequate for a daily driver and could accommodate a sizeable GPU if required. The problem is that the smaller builds are still niche so you have to pay a premium on an appropriate motherboard and power supply.



Yes, there is a standard called PICMG used in “portable/luggable computer” industry - oscilloscope-shaped PCs for field uses. Kontron and Advantech seems to be major suppliers there.


What if GPU makers made motherboards?


I vaguely recall Nvidia motherboards were junk in the late 2000's.


They made motherboard chipsets (nforce, iirc?), not motherboards, unless I missed something.

I think by the late 2000’s, though, their discreet gpus on laptops were problematic because they got so hot they detached from the motherboards or fried themselves. In a lot of cases, these systems shipped with these gpus and intel processors with integrated igpus.

This happened to a thinkpad t400 I had a while ago, the nvidia graphics stopped working and I had to disable it/enable the intel gpu in the bios (maybe even blind).

Iirc this snafu was what soured relations between apple and nvidia.


All the big ones do already.


Sorry, what I meant was, what if the GPU and the motherboard fused into one unit. So the CPU and main memory in but the card is fixed.

I guess the main problem with that we have this cycle where most people have a single graphics card with one or two monitors plugged in, and the power users have two of them to drive four screens, or to have 2 cards drive one monitor by daisy chaining them together.

But in the case of the latter two, it's usually a problem of a bottleneck between the card and the main bus, which of course if you were making the motherboard, you'd have a lot more say in how that is constructed.


What if we plug the motherboard in the GPU instead


What if gpu was the motherboard instead?




Back in the days when I was a kid tower PCs were comparably rare and most of the PCs used the horizontal desktop design which essentially is the same like a tower but put on its side. People would often put the monitor on top of it to save the desk space (see the Windows 95-2000 "my computer" icon). Isn't it time for that to return so we wouldn't need “GPU Support Sticks”?

By the way, what actually dissatisfies me is the majority of mainboards having too few PCIex slots. Whenever I buy a PC I want a great extensible future-proof mainboard + very basic everything incl. a cheap graphics card so I can upgrade different parts the moments I feel like . Unfortunately such many-slot maininboards seem to all target the luxury gamer/miner segment and be many times more expensive than ordinary ones. I don't understand why some extra slots have to raise the cost up 10 times.


> horizontal desktop design

That's be a pretty clever solution. I wonder if any case designers are brave enough to try to pitch that solution. Somewhat fits in the rising popularity of putting your tower on your desk.

> I don't understand why some extra slots have to raise the cost up 10 times

Part is market differentiation, but the other part is that you quickly run out of PCIe lanes to the CPU (especially with Intel, thanks to their market differentiation). If the mainboard manages to use no more PCIe lanes than the CPU supports, everything is simple. Once you add more or bigger PCIe slots, more M2 slots or more USB3 ports, the mainboard has to include a fairly expensive PCIe switch to turn few lanes into more.


I see. A very good point. Thank you. This reminds me about the explanation of why do USB-C docks have separate USB-2 ports: because every USB-3 lane has a separate USB-2 sub-lane and these are left vacant after using USB-3 lanes to connect an SD card reader and a NIC internally.

By the way, about brave horizontal desktop PC designs, note a neighbor comment by c0balt mentions one, to it seems very nice, I would buy one immediately if a traveling salesman would knock my office door offering it without the mental overhead of having to order it and wait.


Funnily enough, I happen to sell these horizontal ATX cases door-to-door! Only thing is, I'm a bit far from your area, and I can't stand travelling more than I need to. You'd help me a ton by helping me schedule my way to you, if you've got a few minutes.


> Somewhat fits in the rising popularity of putting your tower on your desk.

I would never want a PC on my desk again. The fan noise would be annoying as hell. Also, the form factor for modern multi-monitors would make them awkward to have sitting ontop of a box like that.

The modern designs are using silent systems like those from Apple with passive cooling, so you're not going to be using a GPU like those discussed here.


My wife has a modern case with a horizontal motherboard: Thermaltake Core V21. It's not short enough to put a monitor on top of (because it uses a dual-layer design with a "basement" under the motherboard for the PSU and HDDs) rather than being wider, but it does at least solve the GPU leverage issue.


Another useful feature of the horizontal desktop design is that putting the monitor on the case brings it closer to a comfortable viewing level.


The problem with cases that are oriented horizontally is they're usually required to be in a slim form factor in comparison to "normal" ATX or even mini ATX cases. This poses a problem for providing adequate cooling and power delivery. In face of GPUs (NVIDIA/ AMD) becoming more power hungry/ heat producing this just doesn't work out for most people. There were some attempts in the past[0] however they don't appear to have gained mainstream adoption. On the other hand, systems with low power components could be accomdated in this form factor but they most likely wouldn't benefit much from it (or just employ a laptop with a dock).





Horizontal form factor might solve the 'at rest' problem, but the moment you pick up the case to move it somewhere (even still while horizontal) the socket it going to be under load. We really need a solution that supports the card well enough that it's safe even in transit.


Because they usually have to use a different more expensive chipset and a lot of stuff uses PCIE these days that didnt before, for example NVME SSDs now take PCIE slots that were free to be used for different stuff before. And in the desktop market, most people just dont need more than a pcie slot for their boot drive and their GPU. Add to that that PCIE 4 and 5 are more expensive and require more expensive boards.


What exactly do you want to expand it with though? Sound cards are dead and everything besides accelerators is USB now.




The thing I don't get is why are we so damn stuck on towers as the default form factor? It's pretty much masochism to mount a sensitive piece of 8 billon layer circuit board vertically and then hang a bunch of blocks of solid heat conducting metal to it from the side, held on only by a soldered on piece of plastic.

Bring back proper desktop cases!


And while we’re at it, let’s bring back rack mount chassis. The rack mount market is appalling at the moment. If you don’t want the volume sales model imported to your region, your stuck getting overpriced models shipped at overpriced rates all the way from the increasingly limited number of manufacturers in china/India/etc, many of which are slowly sliding into overpriced industrial only markets. I bought one at full list price and shipping that had so little care put into it they didn’t even take the protective plastic wrap off the metal subcomponents before slamming them together! All because I wanted a generic 3U chassis to put together a compute node with low profile network cards. I looked at getting an empty chassis to just go open frame drill my own holes and it would have cost more to get a hollow sheet metal tube 3U high than the rack mount unit I bought… ridiculous!


I had a similar experience trying to find shallow storage chassis that would fit in 2 or 3u. Seems like a no brainer to me to have just a rack mount array of 5.25 bays I can put hot swap cages in but nope.


Absolutely! It’s so bad that “custom” rack mounting is one of the reasons I got myself a drill press. Sheet and bar stock is trivial to order cut to simple dimensions for panels, corner bracing and making “rack ears”.

But it still comes back to the fact i shouldn’t need to make a mini metalworking shop in order to affordably mount hardware horizontally in my rack. Rack mount should be the ultimate in “big computer enclosure” but instead of cool things like having a 2/3/4U massive rack mount water cooling radiator with big quiet fans to silence everything in a computer, it’s getting harder and harder to buy any parts for a non-OEM computer that aren’t festooned in RGB and designed for transparent towers with all the structural issues highlighted in the original article.


Right? Floor space is at an all-time premium with high housing costs. And most people I know have a stack of books/etc. to rise the monitor anyway.


Having a ~140 mm tall desktop case under the monitor doesn't work that well with today's pretty large monitors - it would result in uncomfortable viewing angles. Add to that the often very wide monitor stands. And increased cooling noise because the case comes closer to your ears.


Current monitors can be raised on their stand, maybe future monitors could be lowered in front of whatever they’re on top of?


Mount the computer on the back of the screen.


1. While I agree we're beginning to reach absurd proportions, lets really analyze the situation and think about it.

2. Are there any GPUs that actually have performed physical damage on a motherboard slot?

3. GPUs are already 2-wide by default, and some are 3-wide. 4-wide GPUs will have more support from the chassis. This seems like the simpler solution, especially since most people rarely have a 2nd add in card at all in their computers these days.

4. Perhaps the real issue is that PCIe extenders need to become a thing again, and GPUs can be placed in an anchored point elsewhere on the chassis. However, extending up to 4-wide GPUs seems more likely (because PCIe needs to get faster-and-faster. GPU-to-CPU communications is growing more and more important, so the PCIe 5 and PCIe 6 lanes are going to be harder and harder to extend out).

For now, its probably just an absurd look, but I'm not 100% convinced we have a real problem yet. For years, GPUs have drawn more power than the CPU/Motherboard combined, because GPUs perform most of the work in video games (ie: Matrix multiplication to move the list of vertices to the right location, and pixel-shaders to calculate the angle of light/shadows).


> 2. Are there any GPUs that actually have performed physical damage on a motherboard slot?

I have a MSI RTX 3070 2 fan model. It hasn't damaged my PCI-E slot (I think), but it's weight and sag causes some bending that now makes it so that my fan bearing makes a loud noise if spun up high.

My solution has been to turn my PC case so the motherboard is parallel to the ground and the GPU sticks straight up, eliminating the sag. Whisper quiet now.

If this is happening with my GPU, I shudder to imagine what it's like with other GPUs out there which are much bigger and heavier.


Yeah, I do that for a long time. Had a few accidents where I panicked until it turned out the card was just sagging and the PCIe connection was being stopped.

After it happened the 3rd time I just cleaned up a little space and put the PC lying on its side. Zero problems since then.


I've seen a lot of people ignore which screws they're using to retain their GPU

The screw should have plenty of surface area to properly secure the card. You'll still have _some_ sag, but my 3 pin 3090 doesn't sag half as badly as examples I've seen of much smaller cards


I have an EVGA 3070 and also had the sag issue. My case came with a part to support the GPU though, but I didn't realize until I solved it another way: I just doubled up those plates that you screw the GPU into so there was no way it could pivot and sag.


> 2. Are there any GPUs that actually have performed physical damage on a motherboard slot?

Yes. I've seen both a heavy GPU and an HSM card damage a slot. One happened when a machine was shipped by a commercial shipper. The other happened when the machine was moved between residences. It doesn't occur to people that the mass of a card swinging around is a problem when the case is moved.

The HSM one was remarkable in that it was a full length card with a proper case support on both ends.

Also, this isn't just about damaging the PCI-E slot. Heavy cards bend PCBs (both the MB and the dangling card) and bending PCBs is a bad idea: surface mount devices can crack, especially MLCCs, and solder joints aren't flexible either. No telling how many unanalyzed failures happen due to this.

If you have a big GPU don't let it dangle. Support it somehow.

Another area where the conventional layout is struggling is NVME. They keep getting hotter and so the heatsinks keep getting larger. Motherboard designers are squeezing in NVME slots wherever they can, often where there is little to no airflow...


> One happened when a machine was shipped by a commercial shipper. The other happened when the machine was moved between residences. It doesn't occur to people that the mass of a card swinging around is a problem when the case is moved.

Huh. Good point. I'll be moving soon, and have kept the box my case came in as well as the foam inserts for either end of the case. I might just remove the GPU and put it back in its own box for the move, as well. Thanks for bringing that up.


> If you have a big GPU don't let it dangle. Support it somehow.

Or remove it. Takes five minutes to unplug and unscrew a card. Had to do that with my 6900xt recently while moving.


2. We crossed that point generations ago. High end GPU owners are advised to remove GPUs from their system before transporting it and PC communities get posts often enough of people who had consequences from not doing so. Over a longer term even a lighter card can deform motherboards - I had a 290x which did so to an old Z87 motherboard over 5 years with the result the motherboard was no longer flat enough to mount the backplate of a replacement cpu cooler to.

4. Don't forget high end GPUs are also getting longer, not just thicker. So increasing sizes both give and take away weight advantages


> PCIe extenders need to become a thing again

PCIe extenders are a thing already. Current PC case fashion trends have already influenced the inclusion of extenders and a place to vertically mount the GPU to the case off the motherboard.

GPU sag is also a bit of a silly problem for the motherboard to handle when $10 universal GPU support brackets already exist.


I have one of these for a much smaller card, mostly so that cold airflow from the floor intake fans actually has a path to get up to the RAM and VRMs. This is a workaround for a case that doesn't have front intake, which is preferable in my opinion.

It does look a little cool, but I always worry a little about the reliability of the cable itself. Does it REALLY meet the signal integrity specifications for PCI-E? Probably not. But, no unexplained crashes or glitches so far and this build is over 2 years old.


LTT has a video where they tried to see how many PCIe riser cables they could string together before it stopped working.[1] They got to several meters. Maybe you could argue that it's worse inside a PC case since there's more EMI, but it seems like your PCIe riser cable would have to be very out of spec before you'd notice anything.



My proposal isn’t too different. Move the one ultra-fast PCIe slot to the top of the motherboard. It would be mounted so the GPU plugs in parallel to the motherboard, on the same plane, above the motherboard on a tower case. The few other PCIe slots that exist can stay at the bottom.

Only downside is the case has to be taller. Not sure if that would be considered a problem or not.

This doesn’t really help dual GPU setups, but those have never been common. I don’t have a good solution there. I guess you’re back to some variation of the riser idea.


Not a bad idea however you have hard limits on how physically long the PCIe lanes can be. We had problems making sure we hit signal budget for a PCIe gen 4 slot on an ATX motherboard. The problem (PCIe lane length) gets worse as the speeds increase.


My hope was it could similar length to today, just on the other side of the CPU.

Thinking about it though isn’t that where a lot of motherboards put a lot of their power regulation circuitry? I’m sure something would have to move.

But excellent point. That could easily bet a much bigger sticking point that I didn’t really consider too much.


On a further note, why does it even have to be inside the case? Make a slit in the case on the top, so that the PCIe slot is sticking out. Stick a GPU in that slot, supported by the case. The GPUs these days look much cooler anyways.


Briefly, EMI.


> Only downside is the case has to be taller

Not necessarily. A flexible interconnect would allow the GPU to be planar with the MB; just bend it 180 degrees. Now your GPU and CPU can have coolers with good airflow instead of the farcical CPU (125mm+ tall heatsinks...) and GPU cooling designs (three fans blowing into the PCB and exhausting through little holes...) prevailing today.

My idea is to separate the whole CPU complex (the CPU and heatsink, RAM slots, VR, etc.) from everything else and use short, flexible interconnects to attach GPUs, NVMe and backplane slots to the CPU PCB, arranged in whatever scheme you wish.


I was kind of hoping doing it that way would let you put big CPU style coolers on the GPU parts with a lot more height than a 1x or 2x expansion slot.

If you “folded” the GPU over the CPU to save height I would think that would be worse than today for heat.

Maybe I’ve got this backwards. Give up on PCIe, or put it above the rest of the motherboard. The one GPU slot, planar to the motherboard, stays below. Basically my previous idea flipped vertically.

The other PCIe slots don’t need to run as fast and may be able to take the extra signal distance needed. The GPU could secure to the backplane (like my original idea) but would have tons of room for cooling like the CPU.


>This doesn’t really help dual GPU setups

They are with the people who spend the most money on GPUs


Are they?

Seems with the last GPU generation most enthusiast websites recommend to go for a bigger card instead of going SLI.


Yeah, I have a motherboard with a bent out of shape port because of the weight of the card in it. My current desktop has a sag of easily half an inch at the end of the card and it’s not even a particularly large one by current standards. The ATX spec obviously wasn’t designed with GPUs this heavy and this power hungry.


historically cases had a bracket at the front to support full length cards. I even remember I once had a reference amd card that had an odd extension so that it would be supported by the forward full length brackets.

I have to admit I have not seen that front bracket for a long time. some server chassis have a bar across the top to support large cards. this would bet great except gfx card manufacturers like to exceed the pci spec for height. that bar had to be removed on my last two builds. now days I just put my case horizontal and pray.


I came here to mention the front support bracket. You'll find it on the larger AMD workstation cards more often than others, I first remember it on a FirePro reference card, and some searching turned up examples of it for the AMD FirePro V7900, and a few other models.

I've also had the vertical clearance issue since I try to rack mount all my gear now I've got a soundproof rack, its very annoying to need more than 4U of space just to fit a video card in a stable vertical orientation.


Gpu sag is a big issue in gaming computers. I had a small (by comparison and of more contemporary graphics cards) rx480 and bought a cheap 10 dollar graphics card brace to reduce its strain on the pci slot in 2021 to help reduce its chances of failure during the shortage. I use the brace to hold up my new ampere card now (which is maybe twice the length of the rx480).


> Are there any GPUs that actually have performed physical damage on a motherboard slot?

It's quite common to suffer damage from movement, especially in shipping, to the point where integrated PC manufacturers have to go to great lengths to protect the GPU in transit.


How about we move to external only GPUs with huge connectors? If GPUs are half the size, power consumption and price of a PC now, they might as well be a separate device. As a bonus the rest of the motherboard & PCs actually get much smaller. A PC without any spinning disks could conceivably just be the size of a NUC by default, something you can travel with when you don't need the beefy GPU.


The most expensive part of GPU operation (power-wise) isn't computation, it's actually moving information around.

Moving the GPU further away from the CPU and storage is going to lead to worse latency and power requirements.

Over the next 10-15 years, we'll probably see CPU+GPU packages become mainstream instead of CPU (with basic integrated graphics) and a separate GPU.


The most expensive part of GPU operation (power-wise) isn't computation, it's actually moving information around

I doubt that. Compare the GPU temperature (a good proxy for power consumption) when playing a game or doing GPGPU stuff vs playing a video (without GPU acceleration, so it's just acting as a framebuffer). The former involves far more computation, and gets the GPU much hotter.


No. There was an internal nvidia presentation from a few years ago that stated that moving data was the hard part. (I can't find the presentation any more, but if anyone can find it, please post it below.)

Previously graphics cards were essentially designed with a single area of the card handling computation, and another area holding memory. Data would need to be moved from the memory, to the computation area, then back again if there were changes that needed to be stored.

As the computation and the memory demands became larger, those areas had to handle more, but so did the bus between those two areas. What was a negligible overhead for the bus became more pronounced as it had to handle more data.

Eventually the energy overhead of transporting that much data across that distance started constraining what was possible with graphics cards.

That is why graphics card architectures have shifted over time to place memory cache units next to computation units. The less distance the data needs to travel, the smaller the power requirements. It's also led to the investment and adoption of stacked memory dies (why grab data from 5cm away in the x-y plane when we can stack memory and grab data 5mm away in the z-direction).


Given that every Mac, AMD-based XBox and Playstation, and a chunk of the Ryzen market are shipping decent unified CPU/GPU combos, I would say that day is mostly here.


> Over the next 10-15 years, we'll probably see CPU+GPU packages become mainstream instead of CPU (with basic integrated graphics) and a separate GPU.

its already the case with arm socs.


But home PC users / high end GPU buyers (rightly or wrongly) are fanatical about modularity. The server market will likely (has already?) shifted.


I’m inclined to say that’s more due to integrated gpus not being a good replacement if you need CUDA or play games; If a better combined alternative existed (and not at an outrageous price) I don’t see the majority skipping it die to lack of being modular.


I think what the OP is suggesting is that PCs should have external PCIE connectors for plugging in GPU modules.


The problem with external gpus is that the pcie5x16 slot requires signal integrity chips every 5 inches or so [1]. Even for pcie4 it's bad, many people had blue screens or boot issues when using pcie3 only rated riser cables with a pcie4 video card, even though electrically they have the same connections. So, having a huge cable with x16 lanes of pcie5 on the back of the computer doesn't seem that feasible. Maybe fiber optics could be a thing.



Fiber optic would have higher latency vs. copper. Not sure how much of a difference that would make on a bus but I would assume the timing is pretty tight.


I remember linuxtechtips using a meter long wire to connect a 3090 to a computer and it worked flawlessly.


3 metres, not to mention it wasn't a single cable, but a bunch hooked up to each other. Though I believe that was PCIe 3, so 4 might be more picky.


You can easily buy a NUC ECE (size of a graphics card) and use a pcie cable to connect to an actual card. This is my plan for my next machine.


How would that work? I admit I never even thought of PCIe cables, thought it was always just a physical slot you have to put stuff in.


there are PCIe riser cables that you can imagine as an extension cord for a PCIe slot. they're popular in some thin server chassis or in miniITX builds where the form factor dictates the GPU must be in a certain orientation to fit.

there's also the method of external GPUs via Thunderbolt (which carries PCIe) that is more practical for putting a GPU in an entirely separate enclosure


Ok so just plug your computer into the GPU ;)


I wonder how far that connection could be before it stops working. Probably not much!


Here is an LTT video about how many PCI-E extensions one can daisychain without problems.

The limit is around 3 meters.


One should note that it will works way worse with higher pcie versions of today


Isn't this what the thunderbolt enclosures with GPUs are trying to do?


I’m pretty sure Thunderbolt only has the equivalent of 4 lanes of PCIe 3.0 while GPU cards tend to be 16 lane.




Could we just follow the atx spec? There is a maximum length for expansion cards, and at that end there are optional supports. These are in servers already. Just start using all that case volume to support the GPU.


Cheers, bravo, exactly what I wanted to say. However just to be pedantic, I just read the atx spec to find this exact information and it is not there. I suspect the expansion card dimensions are in the pci spec.


Is that the same as the one shown in the article's spec diagram, or something different again?


My case has these and I would love to know the proper keywords to find extension brackets I could add to my shorter cards. Searching for "extender" returns electrical extenders for the PCIe port itself.


I was always under the impression that was to help stabilize long cards so they don’t sag or fall during transport.

But these aren’t just long cards. They have huge heavy chunks of metal and fans on them in the name of cooling.

Are those brackets strong enough for the job? I remember them being basically shallow plastic slots.


there are $10 brackets that solve all this for most people, not sure why there is an HN panic to suddenly rearchitect the whole PC gaming platform.


I made this GIF to illustrate the point of how large these new high-end NVIDIA Lovelace consumer GPUs are:

This is the ASUS RTX 4090 ROG STRIX. Air cooled, no waterblock. That is a mini-ITX form factor motherboard, hence why it looks so comically large by comparison.

This is one of the physically smallest 4090s launching. Its confirmed weight is 2325g, or 5 ⅛ lbs. Just the card, not the card in its packaging.


There used to be so called PIO motherboards from China. These were slightly larger than ITX and the PCIe connector was 90 degrees rotated so the video card was planar with the motherboard.

And if we are to reform our computer chassis anyways, we could move the PSU to straddle the motherboard and the video card and even have the VRM inside. High amperage "comb" connectors exist and VRM daughtercard motherboards existed Change the form factor so two 120mm fans fit, one in front, one in the back.

So you would have three 120mm front-to-back tunnels: one for the video card, one for the PSU, one for the CPU.




Voltage Regulator Module.


New design: Switch things around and stick the CPU into a slot on the GPU.


Weirdly, this is the design of the Raspberry Pi, wherein the GPU bootstraps the system and brings the CPU up. Though it is a somewhat academic distinction, since both live inside the same chip.


The GPU should be the motherboard, and everything sticks onto it.


This is gpu manufacturing "wet dream" endgame


So how would multi-GPU setups work?


Multi-gpu setups for gaming are dead.

Multi-gpu setups for computation could have two SKUs one "motherboard" SKU and one connectorized SKU with the connector NOT being PCIe (after a transition).

They already do multi-form-factor, PCIe and OAM for AMD, PCIe and SXM for Nvidia.

Just drop PCIe, have a large motherboard SKU with a CPU slot and some OAM/SXM connectors in quantities up to what a wall socket can supply in terms of wattage (so, like 1 or 2 lol).

Vestigial PCIe cards can hang off the CPU card, if they're even needed.

High speed networking and storage is already moving to the DPU so these big GPUs, unhindered by the PCIe form-factor, could just integrate some DPU cores like they do RT cores, and integrate high speed networking and storage controllers into the GPU.

Home user? You get 1 or 2 DPU cores for NVMe and 10-gig Ethernet. Datacenter? 64 DPU cores for 100-gig and storage acceleration. Easy-peasy.


You buy a motherboard with the number of GPUs you want on it.

Or maybe they could devise some sort of stacking system, with each GPU board separate and stacked.




You just re-invented COM-HPC / COM-Express... kinda.


Give it a few years