andrew_yaweb said:
The noise is soft and constant, almost like when you press and hold the keyboard. A soft, tap tap tap tap tap tap. I'd say the rate is about 30 hz. I degragged the hard drive so that it's nice and clean.
Oh well, who knows. I put on headphones and I don't worry about it too much.
From this description it seems most likely, that the sound is after all coming from the graphics card fan. HDs don't give off constant seek noise, it's always alternating somewhat, even when there is heavy paging load (in which case you would notice the game slowing down a lot too). The only thing inside a computer that gives off fairly constant noise within one order of that frequency band, is a fan (for full speed graphics card cooler fan it would be about 60Hz to be exact). Also, it matches exactly the pattern that the noise begins when the card enters 3D mode and stops when it returns to 2D mode (that's how modern graphics card coolers work, they don't operate in 2D mode at all or with much lower speed).
You could check the fan for obstruction and carefully rotate it by hand to see if it makes similar "tapping" noise per revolution. Another alternative is to test if the card supports SW fan speed adjustement with
RivaTuner. If it does, you could manually change the speed in 2D mode to see if it simultaneously changes the sound. If the sound is coming from the fan, you might want to wait for the warranty period if it settles or ask around whether other cards of the same model give off that kind of noise without failing very soon.
What's the make and model of the card btw?
I will read the manual more about controlling the over clocking. The quick start guides, of course, are very lightweight.
Overclocking doesn't create measurably more noise with normal cooling solutions (a rare exception would be a temperature controlled fan that has voltage regulation steps, these are found mostly in laptops, and even then it's quite unlikely that one could achieve a high enough overclock to actually push over a threshold for the next speed grade, since more speed grades are usually not left at the high end of the temp range).