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So, I took my laptop apart because I had to get to the fan to dust it. I put everything back together and it turns on, and starts to boot into Windows but turns off. Any ideas?

Ram: Took out one of two sticks and ran mem check. Check came back fine, but still turning off when starting

Hard drive: Hard drive tests came back fine, and I tried to install a new hard drive with Windows 7, but the installation crashes when starting.

Network Card: Disconnected, still not working.

Update 1: I can fully boot into the OS sometimes, which is weird. Something must be triggering the shut downs. Does anyone think I agitated something that controls the heat sensor? I took a huge glob of dust out by the fan. But now I guess it seems to stay on for short periods of time. Trying to do some more tests to see if this is the problem.

Update 2: I left it laying in front of my air conditioner to install Windows 7 and it hasn't turned off yet. I'm almost certain it's a heat sensor telling the computer to turn off. Does anyone know how to tell or disable it?

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up vote 3 down vote accepted

It's fixed! So when I took it apart to clean out the fan, I took off the heatsink as well since they are connected to each other. I took so much dust out, that I couldn't believe that it was a heating problem, but it turns out it was. I took it apart for the sixth time in eight hours and took some hydrogen peroxide (not sure if it's the best for electronics) and just used a cotton swab to clean away the top of the CPU. I then had some really really old thermal paste laying around, and since I was desperate I gave it a try. Some "water" came out at first, and then the thermal paste. I spread it around, and now my computer works perfectly and the fan runs smooth as butter. Awesome.

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If you detach a heat sink you must always replace the thermal paste. – Scott Chamberlain Jul 22 '12 at 15:00
Ohhhhhhhhhh. I did not know. Thanks! – EGHDK Jul 22 '12 at 22:12

There is a heat sensor in your computer. From your description I'm sure that's a heating problem. I guess that if you leave it overnight it will turn off after about half an hour...

Are you sure that your fan is clean from dust and turns freely? Does it blow air? Actually, are you sure you reconnected its power source?

Changing your fan will be the perfect solution IMHO

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