Only sound is a high pitched noise after GPU driver install

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.

Thanks.

EDIT: It seems that the noise is still there when the computer is off. Only shutting down the power supply causes it to stop.