PSU delivering less power?

Hi,

after 2 hectic days, I have the feeling my PSU is dying.

Yesterday, all of a sudden, one of my disks (disk 5) became unavailable. Checking the logs, it made me first suspect a cable issue, so I changed the SATA cable, restarted the array, and rebuild started. During the rebuild, it failed with another disk (disk 1) showing as unavailable (resulting in loads of read errors in the logs).

So I though I might have touched the cables , checked and pressed on each of them, restarted the array, all disks here, disk 1 SMART test OK, rebuild starts, then fails after a while on disk 5. I changed the SATA port where it was plugged, restarted, rebuild restarts but failed again on disk 5.

Since I had a spare disk, decided to replace disk 5. Restart, and now, disk 1 throws thousands of read errors on rebuild. Stopping the rebuild, try to access disk 1 attributes & capabilities tabs in the UI, but it's all empty.

As I had tried different SATA cables and ports, decided to plug disk 1 on another power line.

Restarted the array, all disks up, no errors, rebuilding is running for 2+ hours now (~80MB/sec), where incidents were occurring in the first minutes, and SMART attributes are fine on both disks.

Since the power plugging of the drives didn't change in months, I would suspect the PSU is giving less power ; is it possible?

My PSU is a 11+ years old Seasonic 460W Fanless 80Plus Platinum, properly sized (checked various online PSU calculators, all estimates are under 350W where the PSU efficiency should be around 414W).

So, do you think this could be the PSU not being able anymore to provide enough power?

If so, any good suggestion for a good, silent PSU to use?

Thanks!