Here’s a real weird issue I’m having with my computer’s power supply. My old PSU blew up last week so I went and bought a shiny new CoolerMaster “eXtreme Power” RS-430-PCAR.
Even though it cost twice as much as a generic PSU, I thought I’d get it because it claimed to be very quiet.

It was indeed fairly quiet - for the first hour. Then it started making a high-pitched squealing or whistling noise which set my teeth on edge much like fingernails down a blackboard. All the voltages tested fine and the PC was working perfectly, I just couldn’t bear to be in the same room with it because of the noise.

But now it gets even weirder. I sent the thing back under warranty. UMart were very good about it and replaced the PSU even though they said they could see no problem with it. However when I connected up the new unit, the squeal was still there. Bah!

So I tried it in my old PC where it ran perfectly for 24 hours with no squealing. The old PC’s PSU which is just a cheap Taiwanese thing, runs fine in my new PC so I have simply swapped them.

I’m guessing some kind of oscillation occurs when the PSU is loaded in a particular way depending on the type of motherboard. With all drives and stuff disconnected, it works fine on my old motherboard (an ASUS A7V266) but will squeal with my new Gigabyte 7VT600P-RZ. The squealing noise warbles when the disk is being accessed which supports the theory of the problem being related to the load. I’ve no idea what I can do about it but it just goes to show that buying brand name equipment is not always a good thing.