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Suddenly my computer has begun to power cycle continually with no end in sight until I physically remove the power cable from the PSU. This has begun spontaneously and not on the back of any hardware or software changes.

The PC will "boot" for about 3-5 seconds - fans start spinning and LED's come on, and then turn off abruptly. After about another 3-5 seconds, fans start spinning and LED's come on, and then turn off abruptly. This cycle continues to infinity.

Immediately I thought the PSU was to blame, but upon swapping it out for a brand new one the issue persists.

I have tried a myriad of hardware troubleshooting combinations to diagnose this issue:

  • Motherboard with just CPU
  • Motherboard with CPU / RAM
  • Motherboard with CPU / RAM / GPU
  • Motherboard with CPU / RAM / GPU / HDD

(Both in and out of case to negate any potential shortages)

None of these have had any effect whatsoever on the issue.

Also, when I remove the 6 (or is it 8?) pin connector which powers the CPU and attempt to boot, the cycling stops and the fans stay on. Obviously, however, the system will not properly boot without this plugged in.

The motherboard is a Gigabyte GA-EX58-UD3R. From googling it seems that this is quite a widespread issue particularly among Gigabyte mobo owners, but nobody seems to nail down a cause.

I've taken the CMOS battery out for tonight, but I'm not hopeful!


The CPU input I'm talking about is here:

enter image description here

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any beeps/boops/other sounds? you'd need to have your PC speaker plugged in, of course. Also, isn't the CPU power input 4 pin? – Journeyman Geek Sep 23 '11 at 23:34
@Journeyman Nope, no beeps. The input I'm talking about is here: – Lumber Sep 24 '11 at 9:20
ahh, guess they got bigger in the 4 years since i built a system ;) – Journeyman Geek Sep 24 '11 at 14:46

Just by looking at your trouble-shooting steps it looks like a MoBo issue. It's the only constant in all of the different things you have tried. There is probably a short somewhere, bad solder, or a faulty power connector on the MoBo. I'd try swapping it out and keeping everything else the same, see if that fixes the issue.

It especially seems apparent that the MoBo is the issue because you say that a number of people with the same or similar MoBo are having the same problem. So that is likely your point of failure.

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I agree, seems that the motherboard is almost definitely the culprit. I'm just hoping there is a fix which doesn't necessitate me RMA'ing the mobo – Lumber Sep 24 '11 at 9:21
After taking a look at the picture and the additional info you provided, I would say that the problem is pobably somewhere in that CPU power connector. It's either an issue with the connector on the MOBO, the connection between the CPU and the connector on the MOBO, or the cable. If you can get your hands on a spare cable you could try swapping it out, but to be honest I think your going to have the RMA the MOBO, it could be the CPU but if it were me I would swap the MOBO first, unless you have a replacement CPU on hand that you can use to swap out and be 100% sure its the MOBO. – Dan Sep 25 '11 at 7:39
BTW, Nice looking system. :) – Dan Sep 25 '11 at 7:39

Either the Motherboard or CPU is defective, you can't pinpoint which without replacing one.

You should definitiley try to replace the motherboard first, which is more likely to have the error...

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