My computer has shut off three times by itself without any power outages.After the third time I noticed the heatsink fan was turning too slowly.I swapped the fan with one from another computer and it turned slowly also.The power supply is putting out 12 volts through the yellow wires and 5 volts through the red wires.I checked BIOS and the fan was running at 750 RPMs.I switched off the ‘smart fan' allowing the fan to run continuously at 4500 RPMs, which is too loud for my purposes.The CPU temperature stays around 20C and the system temp is around 32C according to BIOS.When I enable the smart fan, the CPU temp and the system temp rises but the fan speed slightly decreases.I think I have eliminated the fan and the power supply as being the problem.I think the system temp is accurate but not the CPU temp.Any thoughts as to what is happening other than the CPU is failing?The computer is about 4 years old.Time to buy another one?EMachines EL1850G-42w Intel Celeron E3400 Windows7