Alright, so I built a custom tower about 2 years ago, everything was working beautifully until yesterday. I was messing around with Blender 3D when my computer shut off on it's own during a render. I try turning it back on, but no go. It responds with a single twitch from the PSU and System fan, as well as a quick flash from the LEDs.

I took it apart and tested it with nothing but the Motherboard and PSU. Same response. I noticed that if I unplug the 8 pin 12v ATX cable and leave the larger ATX cable plugged in it will run a little longer(about 1 fan rotation), before quitting. Repeatedly, after about 4 seconds it will turn on again, and shut off just as quick.

My first thought was the PSU, so I brought it in to have it tested at our local computer store. The man there concluded that the PSU is good. So I'm guessing it's my motherboard... fun.

My question is, with all this said, what possibly could have happened, and is there something I may have missed in my testing.

My rig:

Motherboard - Gigabyte GA-P55A-UD3

CPU - Intel Core i7-860 2.8GHz Quad-Core Processor

PSU - Sunbeam PSU-ECO750-US-BL 750W ATX12V

Memory - G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 2200

GPU - HIS H567FO1G Radeon HD 5670 1GB 128-bit DDR3 PCI Express 2.1 x16


Even though you know that the PSU is good, try using another one.

I had a Seasonic 430W PSU which did the same thing when I tried booting with a second HDD attached. The PSU seemed to work okay in every other way, even in another machine.

I also agree with the other answer, and I would suggest checking your case cooling and temperatures as a good idea.

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  • This is a possability, I'll try this out and let you know how it works – Bradygg May 18 '11 at 19:23

Try clearing the CMOS, and swap your RAM around.

Perhaps your motherboard turns off automatically if the detected fan speed is zero? If you have to connect the liquid cooler to the fan pins on the motherboard so it can present a "virtual" fan to the motherboard (I have absolutely no idea if this is the case, just an idea off of left field), maybe something with the cooler is defective.

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If it is the motherboard, it could be any number of things. Perhaps thermal cycling caused some piece of lead-free solder to crack, somewhere on the underside of the board, for instance. A capacitor blown? DIP switch jiggled out of position? Speck of dust got between and is now shorting two contacts?

Do a detailed visual inspection, ideally with a magnifier. If you see broken solder or a leaking capacitor, well ....

I assume you removed the RAM when doing your minimal-system test? RAM failure is a damned common problem.

I also suggest unplugging all cables from the motherboard and PSU, then reattaching them. Loose cables are the most common cause of problems like this.

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Heat, most likely. Either warping the board or warping components.

Were you using the OEM cooler on that CPU? If so, back then the Intel coolers weren't really up to running anything more than standard desktop applications. If you wanted to run anything really CPU intensive, you had to get an aftermarket cooler to keep the system running at spec.

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  • No, I removed the piece of junk cpu cooler it came with. I ended up replacing it with a Corsair liquid cpu cooler. The only heat issues my computer has ever had was with the GPU. However I'm pretty sure the GPU wouldn't cause the current power issue. – Bradygg May 18 '11 at 16:56
  • Do you know how much Blender uses GPU extensions for it's processing? – music2myear May 18 '11 at 18:32
  • Blender works more with the CPU then GPU. – Bradygg May 19 '11 at 18:59

It could be a shortcut between the case and the motherboard standoff (the brass cilinders). Try removing the motherboard from the case and power it up.

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  • Tried this but got the same response. – Bradygg May 18 '11 at 17:34
  • So, it could be: cooler not working, bad motherboard or bad PSU. At this point is just trying. – DrNoone May 18 '11 at 21:06

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