I just built an HTPC using a Gigabyte GA-EP43-UD3L MB (BIOS F4), 4 GB Corsair memory, WD Green 750GB HD, E8400 CPU and Asus 4650 video card. I have tried this combo in two different computer cases and under Vista 64 and Windows 64. The operating system successfully shutsdowns, but the cpu fan, power fan, system fans and video card fan continue to spin. The only way to get the complete power shutdown is to depress the power button for 4 secconds.

I have not tried flashing the bios to a later version as it seems others have tried this unsuccessfully and I would prefer to try that as last resort. I have searched the web and found others with similar problems or with other looping reboot problems, but found no suggestions that actually fix this. I am hoping that one of you guys may have some suggestions.