Shuttle SK83G Small form factor bare bones
AMD64 2800 747pin
80gb SATA HD
512 mb Cruical
This is the system.
The problem is with the smart fan system. When first built, the cpu fan would run at the slowest speed, very quiet. Suddenly, the fan won't throttle back to ultra quiet/slow.
I've changed the bios settings, made sure the interior is clean, checked the cpu temp, re-seated the heatsink, and a few more things I can't remember right now.
It's like the thermo-sensor has failed and isn't letting the fan throttle down.