RFI, radio freq. interference can do this. Guess what your system can generate it from weak or poor construction of the mtrbd. or audio circuits. Moving the mouse around can cause this as well. Either the audio portion of your system is set too high or componets are just "iffy" they can't porvide protection against itself. The audio card if so used is too close to a circuit, remount in a different slot. If build-in audio then the mtrbd. is of poor quality. Understand that systems generate alot of "electronic noise" and at freqencies way beyond of older systems, things get complicated. The quality of componets thus is an issue, why some mtrbds. are more costly than others. There can be other sources of noise but usually I blame the above. also, if you "outside RFI" sources like elec. tansformers, ham radio, big speakers, etc. these too can be a problem, its just the modern world at large.
Alrighty... I just built this system 2 weeks ago, and last night started hearing a strange hum from the system. Thought the hard drive might be going, but I can't pin point the noise exactly. Here's the even stranger part... I can be viewing a web site, or files on my computer through Windows Explorer, or Firefox, and when I scroll, that low hum gets a little louder. When I stop scrolling, the hum goes back down. Seems to happen when the system has been on for a while.
Do hard drives spin more when you scroll in a window like an internet page than when you do nothing after a page has loaded? I figured web sites loaded into memory, and therefore no excessive spinning was needed from the HDDs other than their normal spin when power is feeding them.
Also, it couldn't be the processor could it?? Maybe something in the transistors misaligned and is causing the hum? Guesses?
The system is an: AMD Athlon 64 3700+, on an ASUS A8N Deluxe SLI, 2GB of dual DDR400 Corsair TwinX RAM, nVidia 7300GS, and two Maxtor Drives