My powerbook has begun to whirr like hell from the power supply when connected to power (battery is dead so...), even when using Reduced setting. I can now only run for about 2 hours on the reduced setting, doing moderate work, before the screen garbles up and locks. Probably a graphics card overheating.

Have also underclocked the ATI card 30% (!!), no dice. This is my last hope before having to crack it open and slap on some cooling goo :)

I did the opposite, and set my temperature threshold lower in order to keep my computer cooler. This will have a detrimental effect on battery life, but may just save your lap.

This is a fantastic app but just remember to use it wisely. There are sensors on a Mac for a very good reason - so that it doesn't overheat and burn your lap or a hole in your table! I tweaked the settings very slightly and now my fan hardly comes on but it's still at a safe temp.