I have a PNY Nvidia 7600GS graphics card. It has a fan on it. For some reason when I watch a video on youtube in full screen and move the mouse to where the play/pause button comes up, something inside the computer starts making a noise. It sounds like a fan is lightly rubbing up against something. The computer used to do this before, but I recently added a new motherboard and now its doing it again. I doubt its a threat, but I was hoping someone could give me a guess on what they think could be making this noise. Now that I think about it, it kind of sounds like a crickit.

We sure as heck can't hear it...lol. Have you tried removing the side panel to see if you can pinpoint the location of the noise?