Pcie 3.0 x16 can push almost 16GB/s in each direction. Add 4-6 nvme drives to deliver that much for a total of 32 - 40 pcie lanes. Not really an option on Intel platform that tops at 48 lanes per cpu.. it makes a bit more sense with 128 lanes on AMD epyc.

Alternatively you can saturate pcie lanes with gpus and load data from ram