Question: This is the weirdest issue I've ever encountered with my PC. Every so often, my sound will start playing back at a lower volume. This happens when watching video, listening to music, all independently.

It usually lasts anywhere up to a minute, after which it will turn up again.

The weird thing about it is that the volume control in Windows remains at 100%, even though the volume is audibly a lot lower. (No, I'm not going deaf, it's just my PC. I checked.)

I just have no idea where to go to troubleshoot this, even.

I'm using Windows 7 64-bit with an on-board Realtek sound-card.

Oh, just in case someone finds this question on Google or whatever, making sure this is on Do Nothing may fix your problem. Unfortunately, it did not work for me.

![Windows Sound dialog](https://i.stack.imgur.com/vwEgV.png)

My settings all seem fine. This is my audio slider. (Took the screenshot while the issue showed.)

![enter image description here](https://i.stack.imgur.com/1AHLD.png)

Answer: 
For me, the problem was solved by running Windows Update followed by ensuring the drivers for the audio / video card AND the chipset were up to date.
Do you have lots of things sucking juice from the power supply? Maybe a device becomes active then the power flux causes the audio issue?

I have this same problem randomly on my cheap Gateway desktop, but it only happens after I plug or unplug a USB device.

Another less likely thought... do you have any cables laying on the carpet? No lie, I've had static electricity from me walking on the carpet shoot across the carpet (I imagine it like a wave) and cause static/feedback on my speaker wires before.

If it's hardware related though it's more likely a bad sound card or a power supply issue.