One method is to limit maximum CPU clock speed. (Which in turn reduces maximum performance, so not recommended unless your main priority is heat control)

First, do this: (allowing processor to go into lowest power mode when idle, this should not have any impact on performance)
HEAT control when idle
Power Options -> Select Plan -> Advanced -> Processor Power Management -> Minimum Processor State, put 0

Then only this if overheating still is an issue (capping max speed when under load)
HEAT control during load
Power Options -> Select Plan -> Advanced -> Processor Power Management -> Maximum Processor State, put under 100 if it was 100 e.g. 99.
(If it was originally under 100 and it was overheating, you have serious issues)

Highly not recommended to set Maximum processor state too low.

Sidenote: To monitor the CPU current frequency, use CoreTemp (So you can tell the processor clock speed is at a low amount when idle (e.g 1Ghz+) and also find the highest.

This post has been edited by adbacc: Jul 10 2011, 05:56 PM