I have seen builds with multilple GPUs and I would like to know if it is feasible and how can it be done. I have seen motherboards that support two GPUs but what about three? Is it posible? What about the cooling isnt it affected?
Just choose a mother board with multiple PCIe slots… they do not have to be 16x because you feed them at the start and only want the computed data at the end and does not need this “all the time”…
This for example show motherboards with 5 PCIe slots…
It’s not that simple.
If you invest that type of money to buy 3 5080 (which I wouldn’t do since that card is pretty bad in price to performance), you want them not be throttled in any way. Just because Blender isn’t as real time as a game engine, it still can make a differences in loading / render times - especially in big scenes.
How many PCIe lanes are available depends on the CPU / cores first and foremost.
Also there is still PCIe version 4.0 and 5.0 in the mix, make sure you understand their limits / what the cards can actually utilize.
A lot of mainboards split the PCIe lanes up to multiple (in physical length looking like) 16x slots or other slots like NVME. They share bandwidth. I had my asus rog strick 670e configured incorrectly (not 5.0 full 16x on) to run a 5090 (yes, different card) and it had a big impact on how Blender (OptiX) used that card.
Another thing: 2 5080 cost more than one 5090 but have the same amount of VRAM. Their GPU clocks are not just double because there are 2 of them. 3 5080… I am not sure they will just run 1,5 as good as just one 5090.
Multi-card setups almost never run hassle-free with diminishing returns.
Also you have to buy a top mainboard / CPU - all energy / thermal evaluation not even included. This is probably not worth doing.
You can always throw more hardware at the problem if you have a huge pile of cash. The economic barriers are much larger than the technical barriers.
If you want to go 2 5080s it’s not so bad. 3 would be hard to find a motherboard that could actually fit them since they each take like 3 slots now and there should probably be a slot in between to let air flow better. If you want to go 3 or 4 you could go with a threadripper pro. Those motherboard have a lot of pcie lanes so you don’t throttle anything and a lot of pcie slots. You might still have to use riser cable and will have to have a huge power supply with a wall outlet that has it’s own breaker, but it could work. The threadripper and motherboard cost way more than a normal cup and motherboard. I think it’s like $3k for the motherboard and $3k and up for the threadripper unless you get it used. Don’t quote me on that. Prices vary per region.
Yes… but the 16x PCIe slot are mostly meant for one or two graphic cards… mother boards just do not have more with 16x… so the motherboard is expensive…
The most data putthrough is needed when using them interactively beause there is constantly some data transfer. So even if cycles may be faster on GPU most of the time the GPU is computing.
As you meantioned maybe one bigger card is cheaper as those motherboards.
For example the mainboard mentioned stated in this article /post mentions
- Explicitly states it supports 4x GPUs.
with four times “just” cost ~1000 EUR
The Assus support site even say:
7 x PCIe 4.0/3.0 x16 slot(s)*
- Support PCIe bandwidth bifurcation for RAID on CPU function.