Have a look in the Bios on the PC health page for the voltages 12v, 5v, 3.3v the 12v is the main one to see and the temps of the CPU and chipset, The other thing I would look at is the GPU temp, use GPUz
techPowerUp! :: Download TechPowerUp GPU-Z v0.2.8. Have you ever cleaned the heat sinks with a can of compressed air?