As PCSpecialist build and sell custom desktops and laptops we can't advise on self builds or competitor builds, you may wish to check out Tom's Hardware which is an open forum.The Ryzen 3990X (64 cores - 128 threads) is so powerful we'd really like to build one (or many) in an ATX-compatible rackmount case. There's many 4U cases such as Codegen V2 4U, Silverstone SST-RM400, CiT 4U. This gives us flexibility as to where to put it.
Apologies! Totally missed the forum you'd posted in.Sorry to be clear, we'd like to buy machines from PCSpecialist. Its just that we'd prefer 4U ATX cases. I'm suggesting PC Specialist add cases such as Codegen V2 4U, Silverstone SST-RM400, CiT 4U to their consideration. Our max budget is about £10k per Ryzen 3990X system.