You could build an infiniband cluster. The 3090 would give you most bang for buck. Though it’s a lot more work than trading out for A100s, and the extra hardware will cost. You can get 9 GPUs on an single epyc server mobo and still have good bandwidth. So we are talking about manually sourcing and building 10 boxes.

But unless you are training stuff and have cheap electricity a cluster probably doesn’t make sense. No idea why you would need ~1800GB vram.

Don’t forget to include memory costs.

128GB+ of ecc ddr5 is not cheap

DDR5 is also not fast enough to make much difference

The real issue is that the consumer cpus / motherboards have very few lanes. DDR5 is plenty fast, but you are probably maxing out motherboard bandwidth with two sticks.

Would not surprise me at all if server CPU inference is somewhere between x3 and x5 times faster.