ATX power supplies cap out at 2kW or so and single slot GPUs require water cooling which moves your price estimate significantly. Also difficult to plumb in adj

ATX power supplies cap out at 2kW or so and single slot GPUs require water cooling which moves your price estimate significantly. Also difficult to plumb in adjacent cards. I think the realistic maximum is four ~300W cards per system, and that still needs water. Your point stands - GPU compute on commodity hardware is very cheap. $10k per 4U quad GPU box is probably the ballpark.