The pi is a terrible server and jbod is unreliable. We have a 42u rack now but before that we had a coolermaster haf 932 with 13 12TB disks in it. That being said there are sata HATs and usb 3 to sata adapters.
I really should run some good benchmarks on it. But in an all-core workload I feel like it would hang with a 975.
My ATi GPU collection has gotten pretty epic; the flagship of basically every gen.
Rage Fury Maxx
Radeon DDR 64MB
Radeon 8500...