My computer keeps shutting down

My computer for some unexplained reason shuts down after about 45 minutes. I originally thought it was the Power Unit, so I swapped that out with a 420 Watt Power Unit, but that did not fix it. I ran all of my Norton System Works dianogstic tools and they did not see anything. I did flash my BIOS earlier in the week and experience no problems after that, unitl now. I do not know if they are related or not. Any idea what is wrong?

This question was answered on May 24, 2005. Much of the information contained herein may have changed since posting.

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If your pc keeps shutting off and you have checked the power supply, bios and ran Norton’s diagnostic, you should consider checking the CPU and the CPU’s heat sink.

Sometimes if the heatsink or fan of CPU is not functioning properly it will cause the CPU to overheat and that can power off the pc.

HEATSINK - A device that makes contact with a microprocessor (or other object in need of cooling) and removes heat by exchanging it with air in a more efficient manner than the flat surface the heat sink is attached to The heat sink does this by providing more surface area than a flat surface This is usually accomplished by having a group of fins built into the shape of the heat sin, the longer the fins, and the more of them, the higher the surface area, and the better the efficiency Most heat sinks are aluminum for cost and weight reasons Copper heat sinks are more efficient, but are seldom used because they are much more expensive, heavier, and harder to build It is common for a fan to be mounted onto a heat sink to increase the efficiency of heat exchange by blowing cooler air through the fins on the heat sink.

If need to install a new heatsink/fan you may want to contact a technician or you can do the following:

Install the Heatsink-fan

Note the step on the bottom of the heat-sink fan It is there so it can step over the raised back (left in above shot of the socket) of the socket) The heat-sink to the right would be flipped from right to left to match the socket Once flipped, the right side with the smaller clip is attached first to the left side of the socket The object here is to get the three lugs on the socket into the three holes on the retaining spring without exerting any measurable force on the CPU and to keep the heat sink as close to parallel along the sides of the socket where the Heatsink does not attach to the socket as can be managed If you are not careful, the processor can be broken Repeat; do not apply force directly on the CPU Push and orient the spring through the heatsink and patiently work into place If you use a tool such as screwdriver to assist be careful not to apply too much force and not to let it slip off the spring and damage the motherboard Take your time It will eventually go where it should without damaging the CPU or motherboard, if you are patient Try not to twist or wiggle the heatsink while doing this You do not want to disturb the compound on the die at this point.

Once the left side of the spring is attached, carefully lower the Heatsink onto the CPU, making sure it does not ride up on the step to the right of the socket Again, do not apply direct force on the CPU Let the spring do that One thing about of heatsink-fan is the other side of the spring has a large enough surfaces that is can be hooked to the socket without resorting to tools Hold the part of the spring previously attached to the socket, to keep it in place, and the heatsink-fan with one hand and attach the spring to the three ears (out-down-in) without putting excessive pressure on the CPU Try not to wiggle the heat sink, which, ideally, will come into contact with the die once as the spring is attached Patience is again the key in doing this successfully

Inspect the Heatsink Look along the sides and make sure it is positioned properly and not riding up on the step.

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Posted by Johanna of Katharine Gibbs School - New York on May 24, 2005

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