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PC won't post after power outage

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a b B Homebuilt system
February 23, 2012 1:47:57 AM

Need help.

I placed my PC on sleep this morning then went to work. I came home just got in the door and the power to the house went out for 5 seconds and came back on. (We're in the middle of a heavy rain storm tonight)

Anyhow I get settled about 30 minutes later then go to turn on my PC. When doing so the PC does not post. The screen is black and remains black indefinitely. The fans are running but nothing else is going on.

I unplugged the power cord, held down on the power button for 2 minutes, plugged the power cord back in and tried to boot and the same thing happened.

My Theory: When a computer is in sleep mode all of the active data is transferred to memory for quick wake times. If the power went out then all of that data was flushed from memory. Upon booting it searches for that data which is not present thus has nothing to react to.

Does this seem correct? If so how do I get out of this situation?

P.S. The surge protector it was plugged in to has been reset also.

More about : post power outage

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a b B Homebuilt system
February 23, 2012 2:56:23 AM

Well, one part of your fear is unfounded: When you put the machine in sleep mode, it saves its current state to the RAM - or in other words, a COPY of certain "moving parts" that are active at that moment - and then maintains them with a low level of power. If the RAM loses power and is wiped clean, you'll lose things like ... a document that you haven't saved yet, but the operating system and the programs themselves wouldn't be affected; they're safe and sound on the hard drive.

In the event of a power surge, I'd be much more concerned about damage to the hardware itself, particularly the power supply or the motherboard, though if it affected one of those it could really affect anything. But without testing the components with known good parts, it's impossible to tell what, if anything, was damaged. If you have the option available, I'd try swapping in some new parts, starting with the power supply.

Since it's a display problem you're having, here's one longshot explanation that could fit your situation: If you have an older machine (3-4 years and up), eventually the battery on the motherboard goes dead, and that's what keeps the BIOS settings from being forgotten. If the machine stays plugged into the wall the whole time, that will keep the BIOS from being wiped, but if you lose power or unplug the machine, it'll go back to factory defaults. Often times, that will make it "forget" where the video card is if the motherboard had onboard graphics; it'll try to default to them instead of whatever standalone video card is there. So, if that describes your machine, try plugging the monitor into the onboard video and if it fixes the problem, replace the battery.

Anyway, that was just a wild guess. It would also help to know the full specs of the machine, so if you've got them, post them.
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a c 78 B Homebuilt system
February 23, 2012 5:45:12 PM

Your best bet would be to try a different PSU first.

Do you know someone you could borrow a PSU from for a quick test?
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a b B Homebuilt system
February 25, 2012 2:23:54 AM

I got it fixed. Dunno what happened. Plugged in my old graphics card and got it to boot to a dos screen.

Some message displayed asking if I wanted to delete the restoration data or boot in to windows. I deleted the restoration data, then afterwards it booted in to windows.

I then shut it down again, placed my HD6870 back in and it worked fine.

Not sure what happened but I am extremely thankful my machine is now running.
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February 25, 2012 6:30:17 AM

try reset on psu
surge protector should protect the PC
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a b B Homebuilt system
February 25, 2012 10:13:33 PM

Best answer selected by rwayne.
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