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I have checked my PSU and it works fine. When I turn on the MOBO, the CPU fan, case fans and the psu fan itself turn on for half a second and then turn off.

The PC remains off. The Bios light turns on for a fraction of a second and the debug led as well (for a fraction of a second). I am using a Gigabyte Z87-UD4H mobo and i5 4670K Haswell CPU.

  • Ensure you've plugged in the CPU power connector. – Sathyajith Bhat Oct 3 '13 at 4:02
  • Is there a powered external USB hub attached to your computer? If so, try unhooking the hub and then powering on from a true off state, that is unplug or turn of the PS, then plug the computer back in or turn the PS on, then turn on the computer. – Damon Oct 3 '13 at 4:05
  • Hi, thanks for the reply. I have plugged the CPU power connector(8 pin) and power to the mobo(24 pin). There is no powered external USB hub. I guess its most likely an issue with the mobo – haran kumar Oct 3 '13 at 15:02
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    @harankumar In situations like yours, it is more likely that you have a faulty power supply, rather than mobo. I assume that you've tested your PSU without any load, and your voltages are OK. But if you put some load on your PS, it fill fail most probably and you will have 12V (rarely 5V line) line undervolted. If this is not the case or your PSU is working fine in another computer, than you can start suspecting your mobo :) – Nikola Dimitrijevic Oct 5 '13 at 23:13
  • Have you checked you used the correct cables, everything is connected correctly? I had the same problem this weekend, connected wrong cables on my new PSU :P – CustomX Oct 23 '13 at 8:28
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Have you checked to see if the PSU is supported with HASWELL? their new power saving states require specific power supplies. I have found this out recently myself as I have experienced no post boot. I have to keep power cycling until it decides to boot. Ive found that disabling the C6 and C7 states do not help either. I ended up changing the CPU boot voltage within the BIOS.

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