you could buy 1 or two of these cases.---- my 2 arrive on Friday I will setup a build and see how they do.
https://bitcointalk.org/index.php?topic=5330379.msg56774805#msg56774805
fill every other slot with a 3090 gpu like this.
Pretty cool case, eliminates the need for risers, but standard slot spacing has become obsolete.
Many cards are now 2.5, 2.75, 2.9 slots, etc. More flexible spacing would be ideal.