dual gpu layout

[mark 11:11]

Hello
so as noted in some of my replies and comments in other threads I'm planning on dipping my toes into the dual gpu game [again my last machine had a pair of Quadro m4000s purely to run more screens lol]
this is both for running an extra monitor without the vram pinning to max clock issue and also lossless scaling frame gen on the second card is something I really really want to try out lol.
before i forget to mention the two gpus in question are.....
1] 9070xt sapphire pure
2]6500xt 4gb sapphire pure/pulse itx

im just having problems deciding how to lay this out physically
so the obvious option is use a riser cable and place the second gpu down the bottom and i would have i think either 1 or 2 slots of space in between the two cards [which would have a couple of usb socket brackets in the space between the cards]

or the other option i can see is rotating my pcie panel on the back of the case [frame 4000] and basically placing the two cards in dual vertical again with the usb socket bracket in between hopefully getting me a tiny bit hopefully sufficient airflow space
temperatures is something im really keen on keeping down, i use noctua case fans and cooler [aircooled all the way]
unfortunately i have a massive noctua nh-d15 aircooler on the cpu so i cant move the 9070xt up a pcie slot space otherwise i would just to get that extra space inbetween them lol.
next issue after i figure out the best physical layout is going to be power cables as my psu didnt come with enough to run the second gpu as well il have to email seasonic and possibly sapphire and some cable companies to see if i can buy a decent cable for this.

so question is really how would you guys lay this out? maybe theres a 3rd option i havnt thought of
im not against having to take the side off to access the hdmi/dp ports on either of the cards i dont mind having to do that if it makes the airflow/thermals better im ok with that lol
any thoughts? other than that im probably wasting a lot of time on this lol yeah your probably right but thats hald the fun of the hobby no? lol
thanks for any answers serious or joke ones all welcome
M

 

[mahius]

Modern consumer motherboards don't support dual GPUs quite as well nowadays. Partially due to not enough PCIe lanes and also modern GPU driver support.
9070XTs can be chonky and cover up PCIe slots and having reduced cooling space.

What motherboard are you using and what other things are plugged into it?

 

[mark 11:11]

asus tuf gaming plus [wifi] x570
i can get the second card to work ive got a slot to put it in and riser cables its more a where in the case to fit it best lol
atm all else thats on the board is a nvme in the two nvme slots and a usb header in one of the x1 slots to feed the front usb c socket [still need to wait for a riser cable to install that literally cant access any of the slots with the gpu in place lol
tbh il only be pulling like 30-40 watts on the second gpu most of what id be doing is using a extra monitor really

half tempted to look into whether i can bifurcate the main pcie slot and get both gpus on that just to free up the other slot for another nvme but i think il skip the extra hassle lol
the second card is only pcie 4.0 x4 so the second slot only being x4 isnt such an issue as it would normally be its only a tiny second card as well its an itx card which is allegedly based on a laptop gpu
i am starting to think i should have gotten a bigger case though

 

[Raelgun]

Modern consumer motherboards don't support dual GPUs quite as well nowadays. Partially due to not enough PCIe lanes and also modern GPU driver support.
9070XTs can be chonky and cover up PCIe slots and having reduced cooling space.

What motherboard are you using and what other things are plugged into it?

Not quite, AMD 670E and I think 870E boards do but 670E has more available lanes

They have a 2nd chip that grants additional lanes

 

[mahius]

Looking at the Asus TUF X570 layout and given the components, slot 1 has the 9070XT and given that it's 3 slots, it look possible that the 6500XT will physically fit in the 3rd slot (i.e. the 2nd x16 slot) below it. But of course that would reduce airflow for the 9070XT a bit. The USB header would then fit under that in the 4th slot (the 6500XT is 2 slots), again slightly reducing airflow to the 6500XT. There is also no mention anywhere that filling the M.2 slots on this board, affects the PCIe slots, so those can stay as they are. That's an option, but not ideal due to blocking off GPU fans, unless I've missed something and something doesn't fit.

If the 9070XT weren't 3 slots, then there would be a bit more space for the GPU to get some air from somewhere, but still not ideal. This stacked configuration is how folks used to run SLI/crossfire back in the day, but admittedly many of them with either watercooling or blower-style coolers for better cooling. Also GPUs used to be smaller back then compared to the behemoths we have now.

A better option, is to use a PCIe riser cable for one of the GPUs to bring it away from the cluster on the motherboard, but whether that will fit in the case, will depend on what case you have. Many cases don't support vertical GPU mounts, worst case you may have to swap out to a different case.

That PCIe x16 Bifurcaction is possible (need to be sure to get one that supports PCIe 4.0) but then needs 2x riser cables and then I don't think the case would have space for both GPUs in such orientations. Usually those slot bifurcators are intended for things like NVMes and such.

Not quite, AMD 670E and I think 870E boards do but 670E has more available lanes

They have a 2nd chip that grants additional lanes

You are correct, some of the top end X870E boards do have a seconds PCIe slot that bifurcates with the first to 8x/8x.

I was just making the point that these types of motherboards are nowadays a rarity, than more mainstream.
Back when SLI/crossfire was common, it was easy to find mid-tier motherboards that supported SLI with a second electrical x8 PCIe slot (that bifurcated with the primary slot to x8/x8).
My previous Z97 build has a £120 motherboard that came with enough PCIe slots/lanes to support 2-way SLI.
And the equivalent to today's top end boards that grant more lanes via a second chip, was the PLX chip boards back then, which gave more lanes to support triple-SLI.

Admittedly, these days the motherboards dedicate a lot of lanes to M.2 storage expansion.
Perhaps a second x8 slot would be more common if we didn't need multiple lots of x4 lanes for M.2s.
Anyhow, in this case it's fine since the second GPU only supports up to 4 lanes of PCIe4 anyway, so no issues or bottlenecking here only having 4 lanes on the 2nd slot.

Back on topic, the large GPUs these days make things very difficult. My 9070XT also covers up one of the PCIe slots on my motherboard, due to being 3 slot. If I wanted a second GPU, I'd look at something like the new Intel B50 Pro, due to being far smaller and blocking off less airflow for the main GPU. Only issue there that it's PCIe 5.0 x8, unlike the x4 that we have here with the 6500XT.

 

[mark 11:11]

yeah exactly as above
ive got riser cables i can even get a whole single slot inbetween the cards using a riser cable
il probably get around to trying it in a few weeks
probably a day or two before i go am5 lol that seems to be my rate of work i get around to doing something just as the thing that makes it unnecesary happens lol.
nad yes i hve both m.2 slots filled and i intend to fill the x1 pcie slot with a 3rd one asap but tbh i think its am5 time soon so.......
stil might hang on to this setup for other uses though so might still end up with 2 gpus in this setup
most am5 cpus have igpu which negates half of my need for gpu number 2 so kinda a double paradox but im enjoying being silly with my pc so il probably still dual gpu it lol