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The Problem:

Every now and then my computer will fail to start when I press the power button.

The Situation When the power button is pressed the system seems to power up. All lights turn on, USB devices flash, and the CD drive will even open and close. On a successful startup the computers fans will max out for a quick second and then power down a tad. This is followed by one beep.

On a bad start, the fans turn on but never power up to max for that split second, and I never hear any beeps or any other noises (good or bad ones)

My Computer My computer is almost two years old and I built it myself. It has a 750W power supply so failing to get power to all components is not an issue It runs 1 graphics card. An AMD 5750 series card that has not been overclocked. The CPU has never been overclocked and runs at its normal stock 3.4GHz The computer never overheats etc

Possible Problems Could this be because of a faulty/going bad power supply?

Could the graphics card not be getting power to the MB?

These are my only guesses. If anyone has any ideas or links to this kind of problem feel free to respond.

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Could be the power supply or the motherboard. But the simplest thing to try is to reseat the two motherboard power connections. Remove both the 24-pin and the 4-pin connections, and then re-insert them. While the PC is powered off and unplugged of course. And while the PC is open, clean out all the dust. – sawdust Jan 5 '12 at 23:19
up vote 1 down vote accepted

Maybe a power connection issue or the motherboard I would first think.

Your computer being quite recent, I would check if you have status LEDs on it, or otherwise other status indicators, and compare with the manual if at least that is OK. That's a quick first step which might give you out the final answer straight away.

If that doesn't help, as you built it yourself, you can check the connections... First remove everything that isn't necessary - try keeping only the motherboard, the graphics card if there isn't an integrated one, the power supply and RAM. If it can't get to the bios at that point and that every connection is good... You can try another power supply, another graphics card, then you should know if it's the motherboard or what depending on how it reacts.

Sometimes it's the small things... When you unplug, unplug a lot - all you can. But anyway, start with the diagnostic tools at hand: motherboard LEDs!

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This sounds like a motherboard post issue. This could be caused by a faulty device somewhere on the PCI bus, a bad CPU, or a bad RAM module. If possible you should test each device and module separately on a working system.

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It turns out that it was a bad USB device (Wireless Keyboard/Mouse Combo) or a bad USB port on the MotherBoard (I am leaning toward the port on the MB).

Someone spilled coffee into my keyboard so I had to revert back to a wired keyboard during the time I was waiting for it to dry and clean it. After a few days I thought

"Hmmm my computer has not failed to start"

That is when I had my AH-HA! moment.

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