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. Uninstalling and reinstalling the video drivers did the trick, but unfortunately it wasn't a simple process, and I originally worried that I deleted other drivers as well.
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 little amount. 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.
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.
EDIT: It seems that the noise is still there when the computer is off. Only shutting down the power supply causes it to stop.
The normal audio output is incredibly faint, and only comes when the analog out speakers are cranked, full blast. It sounds almost as if the signal is bleeding over from the digital output right next to it. Unfortunately, the line-in adjustments had no effect. Thank you though.
Upon further testing, the high-pitched noise is there full-time, from boot up to shut down, no matter what I do in the middle (changing audio channels, etc). Would it be wise to just wipe all the drivers and manually installing them again? I have the same ones on a flash drive.
If you know what you are doing, then yes, my suggestion is to wipe drivers related to audio. However, most audio driver installers automatically remove the conflicting old ones, thus making the new one the default and active, you could also try that before you delete drivers manually.