[powercf]

Can you explain why you need 16/16/16? Wikipedia tells me that one x16 PCIe 4.0 connection has a capacity of 32GB/sec (x8 is 16GB/sec). A quick search shows NVMe drives with a sustained read or write speed of ~2-4 GB/sec. Equally for the GPU - you need to move a lot of data in/out of the GPU to saturate a x8 connection.

[jacquesm]

It's rare to run that sustained, usually it's bursty so the extra bandwidth is very much needed.