Question about a weird power supply hum in a repair last month

Had a desktop in the shop from a cafe in Dayton that would make this high pitched hum only when the CPU was under load. Replaced the PSU with a Corsair RM750x and it went away, but the old unit tested fine on my load tester. Ever run into a PSU that only acts up under a specific motherboard load?

3 comments

3 Comments

victor801mo ago

Seen that before. Sounds like a weird harmonic resonance with the board's VRM. Old unit probably couldn't handle that specific switching frequency cleanly.

bettyh841mo ago

Yeah, that's coil whine from the old PSU's transformer... it gets really bad with certain load patterns. I always keep a cheap motherboard around just to test for that specific noise before I blame the main board. Sometimes a little non-conductive glue on the coils can fix it, but swapping the unit is safer.

abby_carr574d ago

Bettyh84 knows her stuff, I just nod and pretend I'm not glueing my own shoelaces together.