In a water cooled config the cards only take 1 slot. I’ve got 2 3090s and am buying another two shortly. Preemtively upgraded the power to 220v, found a 2kw PSU, and installed a dedicated mini split. I’m also undervolting the cards to keep power and heat down, because even 2000w is not enough to run 4 and a server grade CPU without tripping. When you start accumulating GPUs you also run into all kinds of thermal and power problems for the room, too.
I was fortunate enough to scoop up a bunch of Gigabyte RTX 3090 Turbos. Cheap used eight slot SuperMicro (or whatever), a cabling kit, four 3090s, boot.
Sincere question: Is installing and running a mini split actually cheaper than racking them in a colo, or paying for time on one of the GPU cloud providers?
Regardless, I can understand the hobby value of running that kind of rig at home.
I personally haven’t done the calculation. I have rented colo space before and they are usually quite stingy on power. The other issue is, there’s a certain element to having GPUs around 24/7/365 to play with that I feel is fundamentally different than running it on a Cloud Provider. You’re not stressing out about every hour it’s running. I think in the long run (2yr+) it will be cheaper, and then you can swap in the latest and greatest GPU without any additional infrastructure cost.