Toshiba Satellite L675 heating problem

This unit was working fine then one day it overheated and shut down, the fan seems to be spinning fine and I used compressed air to blow out the vents. The CPU usage with showing with both Speedfan and Task Manager shows very low, almost non existant when the laptop is idle. I can feel the lower middle area under the laptop getting a little heated soon after the laptop is turned on. So if it's not the fan or processor then only thing let I am thinking would be the graphics chip? If so, is there any way I can know for sure or any way I can narrow this down to see what's exactly at fault?

via Bleeping Computer Last 20 Posts http://www.bleepingcomputer.com/forums/t/510921/toshiba-satellite-l675-heating-problem/