[michaelt]

> The RTX 4090 is a ~three slot beast when using air cooling and needless to say rigging up something like the dual slot water cooled 4090s I have at scale is another challenge altogether... How are people going to wire this up? What do the enclosures/racks/etc look like?

A few years ago, if you wanted a lot of GPU power you would buy something like [1] - a 4/5U server with space for ten dual-slot PCIe x16 cards and quadruple power supplies for 2000W of fully redundant power. And not a PCIe riser in sight.

I share your scepticism about whether it's common to run >2 4090s because nvidia have indeed sought to make it difficult.

But if there was some sort of supply chain issue that meant you had to, and you had plenty of cash to make it happen? It could probably be done.

Some of the more value-oriented GPU cloud suppliers like RunPod offer servers with multiple 4090s and I assume those do something along these lines. With 21 slots in the backplane, you could probably fit 6 air-cooled three-slot GPUs, even if you weren't resorting to water cooling.

[1] https://www.supermicro.com/en/products/system/4U/4028/SYS-40...