Here's something to keep in mind:
I finally found a solution to a problem I'd been having with my video card fan running non-stop. Turns out the standard air-can cleaning I do in my Mac isn't good enough. You need to really take the card out and clean off the heat sync. Take a look at this photo:
http://macsaregreat.com/?p=63
That's exactly what I had! That dust-wall there is where air is supposed to be coming out. Scary stuff.
When it's way back inside the computer that much dust doesn't really look like dust, but just another surface!
This is about the ATI X1900, but other cards may have similar issues. I suggest pulling yours out if you've never done so in the computer's life.
Anyway, I just wanted to point it out because it took me awhile to find this info online. It doesn't seem to be very common knowledge, so remember it and you'll be a little less common.
Hope it helps someone!
