I just upgraded my case fan to a Silverstone FM121 (my stock Alienware fan was making rattling noises). It comes with a knob to manually control its speed/noise. Before I had this controller, my case fan would automatically increase its speed when temperatures rose. It would be relatively quiet while idle, but would become louder upon loading up Crysis, for example. My question is: do I now need to manually increase my fan's speed when I'm running demanding applications? How do I know how fast the fan needs to spin? Does the Nvidia driver for my 8800GTX have built-in functionality to increase my fan's speed if necessary?
What I would like, of course, is to keep the fan as quiet as possible, while keeping the computer as cool as it needs to be. How do I do this?
I stopped doing it. Both amd and Intel have built in sensors either in the cpu or motherboard to throttle back or shut down before damage is done. Amd may have it in the bios. Check the hardware monitoring section for a temp shutdown setting. I set mine at about 70c. I also don't trust most programs for accuracy. If your cpu is overheating, your windows program will freeze or crash. Random reboots can be a power supply or memory issue.
I leave my fans on a constant speed. It is less disturbing to hear a constant speed instead of a increase/decrease cycle. Under load, the cpu gets hotter, but not so hot that it reaches a dangerous limit. I use speedfan to display the temps. In your case, use the knob to get the fan going at a good noise/performance ratio and leave it there. Thr 8800gtx can take a very hot temperature, in excess of 100c. The cards microcode should increase the fan speed if necessary. Use the nvidia monitor to see what is going on to verify this.