Computer turns off by itself

So i built my first computer about 2 months ago, and it has been a harsh ride to say the least. First i had a bad Power Supply, so i got a new 700W one. Then the system would hang, but i got that fixed by resetting the cmos, and then my video card broke, so i got a new one.

Now, i thought all my issues were done, but apparently not. Today i was running my computer from about 1-9ish, and right about 9, it turned itself off, no blue screen, no nothing. I pressed the power button, and the fans came on, but right after post it turned off again. Then it wouldnt boot at all. No fans, no sounds nothing. The light on the motherboard is off, so i take it and i press down on all the connections to make sure they are in, they are. After that my system ran for about 2 hours, but after that it turned off again. It wont boot at all, pressed down on the connections, but still nothing. The light on the motherboard is off, but now it wont boot and ive waited for an hour.

So i think that it is either the power supply, or a short on the board. I dont trust power supplies anymore after my first one broke. But does anyone have any other ideas? There is no fans. When it turned itself off there was no power, no nothing. Ive tried a different outlet, but nothing.

Any suggestions or help are greatly appreciated. Thanks.
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  1. Please provide make and model of your motherboard, processor, video card, and power supply so we can begin to help.
  2. Sorry, my specs are:
    Asus P5Q Motherboard
    Intel Core 2 Duo E7400 @ 2.8Ghz
    2 GB of Kingston RAM
    OCZ 700W Power Supply
    Nvidia GeForce 9800 GT Video Card

    Before it turned off, realtemp said that the cpu was at 34 C idle, and about 41-42 C under load. The GPU was at 49 C, the HDD at 31 C, and the system temp was 29 C, and everest said the motherboard temp was 31 C.
  3. Wow! My first thought is something is causing the power supply to trip out (thermal/overload). Lets discharge the capacitors on the mobo first and see what happens.

    Pull the plug on the psu, and hold the power on button in for a while. Then replug the psu. Do the mobo lights come on now?

    Try to power up. If it won't, I'm gonna believe that the mobo would now allow itself to try powering up, but the psu won't let it. Is the psu very warm? When its running is the psu fan turning?

    The odds of a mobo short occurring suddenly that would allow the system to run for 2 hours and then shut down seems small. I suppose the graphics card might be able to do that, but it seems unlikely.

    It seems you do not have another graphics option, but you could try "running" without graphics at all. If it will run for a long time, we'd know the graphics card is involved somehow, but maybe only in putting a load on the psu that it cannot handle. (But you have a large, good quality, new psu.)

    Are there any other devices that began to be used shortly before the system shut down?

    Dunno what else to tell you at this point.
  4. This is ussually a classic case of an overheated CPU. It's happened to me while debugging with a heat sink just resting on the CPU. Fully pasted and good connection, but somehow it works it's way out. I would recommend the screw down type. Those you KNOW it's a solid connection. Could be another heated component like video chip without a heat sink or some such. You can do it.
  5. Discharging the capacitors on the mobo did nothing, so is a motherboard short ruled out entirely? I'd be happy if it was, cause i dont feel like putting in a new board after all the issues ive been through already. It turned on this morning, but we left to go to DC for the day, but when we got back it wont turn on at all, and all i did was run it for about 10 seconds in the morning to make sure it got past POST. But i think that the power supply is dead.

    When on, the PSU lights up, and the fan is turning. But when it goes out, i cant turn it off until the mobo light comes back on. When it was on i put my hand in without touching any parts to check for any hot spots, but i didnt feel any.

    Now that im at this point, i really have no option but to take it to the repair store that told me my first Power supply was bad, and gave me the one i have now, because i dont have any extra parts around, this being my first build and all.

    I was in DC all day, so sorry that i havent been faster on my response.
  6. No problem on the response lol - believe it or not *I* have other things to do, too lol !

    Sorry, I can't rule anything 100% out, but I like the psu as the culprit because there are no mobo lights until *something* resets. And we did the best we could to get the mobo to reset quickly - and that didn't get us up and running.

    But even if its the psu, I personally can't say whether the psu itself is just tripping out, or if the mobo is drawing too much power (shorting) and causing the trip.

    We tried to jump start the mobo by draining it. Now we could try one more thing - making sure the psu has actually tripped out.

    1. Read all steps before doing anything.

    2. Get the PC to the point where it is relatively recently become "dead".

    3. Disconnect all leads from the psu to all devices.

    4. Read this link - we are going to do what it says with one exception:

    5. The exception: Turn the psu switch off (or pull the plug) before inserting the paperclip. Once the paperclip is secure, turn the psu switch on.

    If the psu fan turns on, then the mobo becomes the likely culprit . . . theory being that if the mobo asked the psu for power, it would have said yes. I don't think this will be the case.

    If the fan does not turn on, then the psu has tripped out, and is waiting for a thermal reset. Why? Can't be sure, but best to suspect a "horse" than to keep looking for zebras.

    Repair shop may be the best option in any case.
  7. It was the power supply. I took it to the shop and they are getting me a new one under warranty. Thanks for all your help.
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