Can't say anything about picoPSU, except writing anything on RAID involves all the drives to seek and write and without a a solid power reserve you can receive a momentary dip of voltage which can lead for a malformed write, but back in mid-late 2000s I've seen enough HDDs failing and corrupting data which miracluosly behaved when moved to another machine or when you replaced PSU (with a decent one, not another $15 chinesium).

A lot of bad reputation of WD from that time is actually from the shitty PSUs, not the drives themselves.