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My machine started freezing (no blue screens, no warnings) after about 30 minutes to two hours of use after a bad lightning storm that also knocked out my router. I've replaced the motherboard, RAM, video card, and CPU after testing out my main OS drive on another machine for a weekend. The new machine will still lock up, though much less frequently, usually lasting between 8 and 24 hours before dying. I'm totally at a loss to explain this behavior, or figure out what I should try troubleshooting to fix the problem.

Here's what I haven't replaced: Power supply SATA cables to drives DVD drive (currently disconnected anyway) Computer case Hard drives (one SSD, two disk drives)

Any ideas on what the most likely culprit is, and how I might test it out? The fact that it takes longer to seize up after replacing everything is pretty baffling to me.

Thanks for any help!

Edit Some more detail if you're curious why I was replacing other hardware before the power supply... after the storm, the main drive was not recognized as a boot drive by the BIOS even though it worked fine in another machine (and I could even boot off the drive when using the Ultimate Boot CD for Windows), leading me to believe that something on the motherboard got hit. I'll try replacing the power supply and see if that helps out. Thanks for the suggestions!

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Test the memory, it is the most fragile part in a PC...memtest.org –  Moab Aug 19 '12 at 17:50
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Is your computer hardwired or using wireless? If hardwired then unfortunately a surge may have come in via the ethernet port and fried your ethernet card (or the motherboard, if it has integrated ethernet). –  Daniel R Hicks Aug 19 '12 at 18:43
    
The last PC I worked on that took a surge eventually had every component replaced as each one died in turn. –  afrazier Aug 19 '12 at 20:27
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1 Answer

I imagine there was another problem that was fixed by one of the hardware replacements. The likeliest culprit would be the Power supply.

I would also check that the fans are functioning properly. Does the computer heat up before it dies? Perhaps the power supply to the fans is intermittent?

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+1 vote for the PSU. This would have been the first component I had checked/replaced as critical surge conditions in the grid would have to pass the PSU fist (and likely causing damage there) before it can damage further components. Especially if the computer was not powered on while the lightning, the other parts (except modems and NICs that could be hurt through other external cabling) should have had better protection. Even if it was running, the PSU should have caught most of the surge. It is not uncommon, that PSUs still work after such surges but the performance might be degraded. –  Gurken Papst Aug 19 '12 at 15:26
    
Agree about PSU. Just because it's the cheapest part that you can try to replace. –  AnonymousLurker Aug 19 '12 at 17:14
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