I have a Western Digital 80GB Special Edition (8mb cache)HD and I've noticed that occasionally (every 20 seconds) it emits a short noise. It sounds like an "activity noise." I looked at the LED light on my computer and the Hard Drive LED doesn't blink/light up or anything when the noise comes, but it sounds like it's coming from the HD. What's going on? Anyone have this problem with their HD? Is it normal? I hear it when it's dead quiet, like at night when I'm working. Thanks for your input.
Try booting the PC and enter the BIOS. In this situation, the HD MUST be dead quiet. No seekings should occur. If there is, there is something wrong with your disk.
The noise you hear may be caused by some background program that occasionally needs access to your disk. I'm not sure why the LED isn't illuminated. Perhaps the duration is too short.