I just put a new computer together, i have an Asus A8N-SLI nForce4 Ultra socket 939 motherboard, with an AMD athlon 3200+.. the computer turns on and goes to the BIOS setup, but comes up with a warning on the bottom of the screen "Warning: Your CPU fan fail or the speed is too low" .. i dont know what could cause this warning, my heatsink is installed correctly.