Ripu

After I shutdown my pc, the fans are still spinning. They spin for about a good minute. I am not sure why it does that. Any ideas?

I just build a brand new pc and i picked a Thermaltake GF3 165W. After shuting down the system everything Ok except power supply that remain lit and when i put my hand behind the unit i can feel the air coming from the fan... not for a while.. like forever. It's like PSU will never stop working... is this behavior normal?