Built a new system as shown in picture below... nothing special, specs are in my sig...
Anyway I put two 80mm fans with blue LEDs in as exhausts, and two normal 80mm fans in as an intake. I was a tad puzzled when I was getting case/CPU temps at idle of 35/42. Couldn't overclock for toffee - I was maxing out at 1.62GHz (AGOGA core)
I've just been and bought some Antec "Reference" silver thermal paste for my CPU because I was using the pad that came with the heatsink. I installed that and put some on my GF4 as well. Then I turned the machine on with the side off, and put my hand near the back. It was sucking air out! :d'oh:
I've turned them round and now I'm getting idle temps of 23/33...
MORAL: Don't throw your machine together just because you're too excited with the jump from a K6-2 w/ V3 to an XP1800+ w/ GF4 - take your time