reboot the computer, and enter setup (usually you need to press delete when the msg "Press <Del> to enter setup" appears)
look for something called "Hardware Monitor"
if you have it, it will tell you the cpu/mobo temps.
also, if you have it, you'll need to configure motherboard monitor to recognise your sensors on the motherboard. ive never seen that program auto-recognise the sensors on install - they didnt with me