Hey all- not exactly sure where this should go so I'll start here.
I just spent a few hours troubleshooting and eventually fixing my GPU (HD 7870). Uninstalling and reinstalling the video drivers and swapping PCI ports did the trick, but unfortunately it wasn't a simple process, and I originally worried that I deleted other drivers as well. I was trying everything at that point, and used both Drive Sweeper as well as cleared out any and all AMD/ATI folders . My suspicions were confirmed when, as soon as I got the GPU working again, my sound was completely messed up. The analog audio, both through the rear motherboard jack and the front headphone jack, were emitting this high-pitched noise which increased in volume when I increased system volume.
Sometimes, a slight amount of playback can be heard along with the squealing, but it's a very low amount, and it can only be heard when the analog speakers are cranked to the max, as if the signal were barely bleeding through from the digital output right next to it. It seems possible that Realtek HD Audio is outputting all of my sound to the digital output (to which there is nothing plugged in), and the analog outputs are dead.
No matter what is done, the squealing is there from boot to shutdown, even if I change the output channel.
Prior to dealing with this whole GPU thing, the sound was perfectly fine, and I'm not great with Realtek either, so if anybody could potentially point me in the correct direction, it would be incredibly helpful. I'm contemplating just wiping and reinstalling all of my drivers at this point.
EDIT: Development- the noise still exists when my PC is off, and doesn't stop until the power supply is shut off.
Nope, removing the 24-pin kills the sound along with it.
Another strange little thing: when the system is off, the high-pitched noise can be stopped if I turn on the backlighting on my keyboard, which is plugged into a nearby USB. It has no effect when hte system is on, however.