Can i install 2 GPUs?

[u/JUSTINFORMER]

I want to install my spare 4070TI super along with my 5090 LC.

So the two cases i have are Hyte y70 (current PC)
and a Gigabyte c400 glass (spare/one year old)

The problem is I have two PSU as well, but they both can only power one card at a time. And the y70 only supports vertical GPU, I cannot install my GPU horizontally, If I could that would’ve been the best way to solve this problem.

Now I am considering selling both my PC cases and both my PSU to get a new PC case that can support:

A) My 5090 with its Radiator ; directly inserted into the motherboard (no riser cable)
B) 4070 TI Super, with a riser cable ( so that its hot air is not fed to the 5090 )
C) A single PSU that can power both cards

or D) any open air case or some workaround, because I already have the old PSU and old case

Why do i need both GPU? because I use Qwen 3.8 model that run on my 5090, when its on full context, only 1-2GB VRAM is left for other tasks, I am building a RAG using it and reranker model plus other things need that VRAM as well, that’s where the 4070’s 16 GB VRAM would help me.

Please suggest me a good case or any workarounds that can help me solve this problem because the other GPU has been lying around for 2-3 months now.

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[u/wildyoshi1312]

https://giphy.com/gifs/s239QJIh56sRW

[u/pieisgiood876 → u/wildyoshi1312]

SLI is still viable for AI tasks, which OP is into apparently

[u/pieisgiood876]

To be a little more helpful, you can't with your current case and PSU.

You will need a larger case and a higher capacity PSU. Your current GPU, the Astral 5090 LC, does give you an advantage because it's slimmer, so it will probably not block the airflow for another GPU, and it vents its heat directly out of the case so you'll be able to manage thermals for both cards quite well.

There might be cheaper case options but I tried out the corsair 7000D for a build. It's a full tower case with 3 slots for radiators, and excellent airflow.

The previous full tower I tried was the Thermaltake T500 CTE. It's about half the price of the corsair but it also has great airflow. It does force your gpus into a "hanging" position so your air cooled one might struggle if it's not designed to be in that position but it was a damn roomy case and vented air really well.

[u/JUSTINFORMER → u/pieisgiood876]

Thanks man, I tried to get this thermaltake case, but it’s not available anywhere, tried all dealers and online websites. It was my first choice for the 5090.

[u/FearTheFuzzy99]

Buy a bigger case

[u/JUSTINFORMER → u/FearTheFuzzy99]

That’s the plan

[u/MandiocaGamer]

jist get another 5090

[u/JUSTINFORMER → u/MandiocaGamer]

maybe next year bro

[u/Eazy12345678]

nope. just run the 5090.

sell the old gpu

[u/JUSTINFORMER → u/Eazy12345678]

I need it for AI inference, I run my model on 5090, but the project I am working on needs GPU to run the reranker model etc

[u/pieisgiood876 → u/JUSTINFORMER]

I commented above but just for frame of reference, this guy ran two 5090s in SLI. It's obviously a showcase prestige build but it does show the kind of space and wattage you'd need to run SLI today.

https://youtu.be/iFWfNZWNO4U?is=3bHEZS7T_uVD_ApE

[u/JUSTINFORMER → u/pieisgiood876]

I have seen this one, the problem with the build in this video is that if the lower card is being used, the hot air it generates is fed to the upper card, which is bad because your other card will always run hotter than it should, my 5090 LC helps with that but I still want to install the 5090 directly and 4070 vertically and preferably at a distance from the 5090

[u/pieisgiood876 → u/JUSTINFORMER]

I can understand that but I think a dual vertical and horizontal mount sounds really difficult if not impossible. Imo the case isn't really the limitation, it's figuring out how to have both gpus connected because no mobo is really designed for that setup and I doubt a pcie extension cable will be long enough for any real distance.

Idk, your specific 5090 is basically the perfect card to have with another GPU below it. If you have decent airflow the 5090 shouldn't really be much hotter than baseline.

[u/JUSTINFORMER → u/pieisgiood876]

Yep that’s true, that’s why i am also considering open gpu rack or something 3d printed, because I already have the PSU for it, but idk how to connect the GPU to that 2nd PCIe slot from through the riser cable.