I just recently built a new machine Gigabyte 945 Intel Duo Core 2.33 E6550 8500 GT Nvidia pci express 1 Gb DDR 667 550 W power supply 80 Gb Sata drive Windows XP SP2 This morning i put it all together and took it into the house to boot up. Everything booted up fine, it posted and everything. I installed the mobo drivers and video card drivers then left the house right after, ( i left the computer on as well when i was gone). I was gone for about 3 hours, came home, computer was still on running fine and sat right back down and started to install all my programs. Then out of nowhere the cpu fan alarm goes off while i'm downloading AVG and i look into my computer and my heat sink fan isn't running anymore. So i quickly shut off the Computer and unplugged it. I looked inside to see if anything might of came loose but nothing. Every time i boot up now the alarm immediately goes off and i look at the fan and it spins in spurts, like 3 seconds spurts. I have no idea what is going on, as i left my computer on earlier for close to 4 hours with no problems. Also to note this is the stock fan that came with the CPU in the box.