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New computer turned off by itself and now won't turn back on :(

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January 20, 2009 11:19:45 AM

I built a new system last month thanks to the help from this message board. I had no problems until today. I often leave the computer in sleep mode, and when I wake up this morning, I move the mouse, the computer starts to get out of sleep mode and then a second later the computer simply turns off. I have a e8500 on a ASUS P5Q and a 750W PC Power and Cooling PSU. I still have a green light on the motherboard but other than that I have nothing. Pressing the power button on the case does nothing at all. I had this computer working fine for close to a month now and never had any problems. :sweat: 
January 20, 2009 11:43:47 AM

So if i understand your post correctly, it no longer turns on? No fans, no nothing?

If this is the case, try clearing your cmos and see if that helps at all. Also recheck all your cables, make sure everything is still plugged in good and snug. Make sure the video card is nice and snug into the motherboard. Seen this fix the exact problem earlier last week.
January 20, 2009 1:00:36 PM

well i wouldnt recommend leaving your computer in sleep mode, you can let it hibernate though...

anyway onto your problem i would start with the most obvious likely cause first and make sure that the PSU is providing the rest of the system with enough power, try a multimeter or another PSU....

this is one of the hardest problems to troubleshoot especially if the problem lies with your motherboard..... as kubes said reset your bios, leave it UNPLUGGED for about 10 minutes and try again...

or server recently did this and it turned out to be the PSU, which is very likely in your case especially as you left it in 'sleep' mode.
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January 20, 2009 1:25:27 PM

The sleep mode was the default setting, so I just left it as is. Actually, the computer would go into sleep mode and I would then forget that it was even on many times. And yes, there are no fans no nothing but the green light on the board. I do have my old 450W PSU from my old system that I can try. Only problem is with my GTX 260 I'm not sure if I should try using that old PSU. Could leaving the computer in sleep mode really have caused a problem like this?
January 20, 2009 11:48:05 PM

Any other thoughts or suggestions on this? How could clearing the CMOS fix the problem? Is there any chance the computer over heated somehow?
January 21, 2009 6:16:59 AM

leaving the computer in safe mode isnt the direct cause.... but leaving it in sleep mode leaves your computer MORE vulnerable to power spikes/dips which could damage your components thats why i suggest you try a new Power Supply first.

clearing the CMOS may fix the problem because a motherboard setting may of been scrambled.

im guessing that your using vista? the power off is next to the sleep mode on the start bar.
January 21, 2009 1:52:28 PM

Thanks. And yes, I have Vista. The sleep mode thing was the default setting so I just left it. Would it be fine if I cleared the CMOS first as that will be alot easier than swapping put a PSU. Also, my old PSU is only 450W. Would that be ok to use real quick just to see it the system would work? I know 450W won't be enough normally for my video card.
January 22, 2009 12:09:39 AM

I cleared the CMOS and even took out the battery and still nothing. No power to anything other than the green light on the board. What should my next step be? Can I try using my old 450W PSU to test it out?
January 22, 2009 1:09:08 AM

Have you verified that all connections are secure? That your rails are properly seated and fully inserted? It sounds very similar to something that isn't quite connected all the way to me.
January 22, 2009 1:20:23 AM

Everything was working fine for 3 1/2 weeks and it shut down when coming out of sleep mode, so to me it seems as if everything is connected. But I could always check again but maybe it's the PSU?
January 22, 2009 1:25:36 AM

Maybe--but before you go all shop-happy and have Newegg deliver assorted parts, it's best to verify what you have. I once had an erroneous heat reading due to a heatsink that had not been completely secured--and one day a corner just came loose. It happens, and we've all been guilty before about little mistakes (note from my lawyer: "Admission of making 'little mistakes' cannot be construed in a court of law to mean that said mistakes have ever or were ever present in the builds of systems I have performed over the years. With the sole exception of an admitted bit of sabotage on a younger brother to deliberately make him lose hair for days, no mistakes either deliberate or accidental can be attributed to me via my previous statements.").
January 22, 2009 1:37:09 AM

I'll check everything again and maybe I missed something. But I would have thought that even if something was loose I would at least get power to the fans or something.. Well, I'll go check everything again......
January 22, 2009 11:29:52 PM

You should try the other power supply. Unplug everything except the video card, 1 stick of memory, and hard drive. Then boot up with the other psu. It should have enough to power all of them. If it boots, you got a bad psu.
February 1, 2014 9:31:30 AM

Instead of removing the PSU, do a test on the PSU by shorting out the GREEN and ground(BLACK) cables on the 20/24 pin ATX connector. Easy troubleshooting method to test for bad PSU.

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