|Download HWMonitor and install it on that computer to monitor the temperatures and voltages in real time. There is no load on the hardware when you are in the BIOS so the temps can be low at that time and still have an overheating issue.|
Best method for cleaning out the dirt/dust is to blow it out using canned or compressed air. Be sure to do the power supply from both ends too. DO NOT use a vacuum cleaner. You and damage components with static discharge.
Try booting into Windows safe mode by hitting F8 at startup.
Did this condition happen all at once or progressively get worse?
Get HWMonitor for the link below.