I haven't kept up with power supply technology at all, on my old PCs that ran Win 95 thru XP, I generally had 250W-450W power supplies that were pretty noisy. The power supply fan ran all the time, and expelled quite a bit of warm air.
On my new PC with Windows 7, I have a "700 watt" power supply that seems to work OK, but I notice that after Windows loads the power supply fan seems to stop running, or runs so slowly that you can't hear it. There is very little air movement coming out. During bootup the power supply fan (I think) whirs and hums like I'd expect; but the instant the Windows7 logon screen comes up, the fan goes silent. Are power supply fans supposed to be variable speed or load-dependent, now? Is the power supply tied in to the OS somehow?
Thanks... although everything seems to be working fine, I don't want to fry my PC and/or power supply.