Out of all the gen4 SSDs, SN850x is the least affected by performance degradation.

https://old.reddit.com/r/hardware/comments/1146b0s/ssd_sequential_write_slowdowns/

RTX A5000 and RTX 5000 ADA is two completely different card.

RTX A5000 is based on GA102 and RTX 5000 ADA is based on AD102

RTX 5000 ADA is a cut down version of RTX 4090 (12800 CUDA cores vs 16384 CUDA cores).

RTX 4090 uses GDDR6x 384-bit bus while RTX 5000 ADA uses GDDR6 256-bit bus

RTX 5000 ADA should be faster than RTX 4080