I have a few RTX 3090 GPU cards and few students working with me. I used to give one 3090 card to one student for running his own experiment on his own computer. Recently, we decide to pool those cards together to one workstation. The solutions from vendors fail to make me happy. So I decide to buy a CPU and a motherboard that can host multiple 3090 cards.
I love RTX 3090. Being a consumer-level GPU makes it more cost-effective than workstation-level or data center-level GPUs like Tesla. And it has the largetst VRAM among consumer-level GPUs.
But it takes three PCIe slots while the ATX standard has up to 8 slots.
Hence, many vendors I found online can only fit up to two 3090s per workstation/desktop – 8 mod 3 = 2. But I have three 3090s and one more incoming. So a dual-3090 solution cannot cheer me up.
Some vendors claim to fit three or more 3090s in one desktop/workstation. Because 8 mod 3 = 2, I would assume that the 3rd 3090 protruges out of the lower/southern boundary of the motherboard. But, this means that all three 3090s are packed next to each other, causing heat dispersing problems. An overheated GPU will lower its clock frequency and thus performane.
There is a special kind of GPU cards using a blower design – the air is blowed out of the computer case thru the PCIe mounting plate (not the slot). Such 3090s take 2 PCIe slots. But still, some of them will be banged one after the other, causing heat issues too.
Liquid cooling for 3 or 4 GPUs is too complicated. You may even run out of space to mount the radiators.
So I decided to search for a solution of my own. All I need is to find a motherboard and a CPU.