Monitor Turns off, computer still on.

I need help... sometimes my monitor will just randomly turn off, and the computer is still on but the sounds from music and videos will sound garbled. The monitor has never done this, and this computer I just built from the ground up. Please if u can tell me what to do thanks. I also have updated everything, the video card wasn't overheating, same with the cpu, the temps were pretty low and I have disabled screensavers, power options for the display. I am using windows vista, and have gotten the latest updates as well.

 

I would maybe start with uninstalling sound and video drivers and reinstall.
This could still be driver problems.

But, this could also be a power problem. I had my speakers plugged into a battery backup and the sound would get all weird on me till I plugged in elsewhere.
Try plugging it into a different power outlet.

I would then maybe check the PSU, garbled sound and a monitor going out like that could be hardware related problems also. It's difficult to tell you where to start on this one.

 

How should I go about checking the PSU?

 

One way is to get another known good PSU and put it in, see if the problem continues.
Get a PSU tester, or possibly take the PSU to a shop and see if they have one they can test the PSU for you. It only takes a few seconds to test with a PSU tester.