New Giga i5 machine wont boot - power cycles

Just built a machine based on a Gigabyte P55A-UD5P board with an Intel i5-750 cpu.

On powering up the Phase LEDs all light up for less than 1 second then the power goes off.
This cycle repeats every 5 seconds.
It doesn't get as far as a POST beep.

It behaves the same way with or without RAM or graphics card installed.

Any suggestions
5 answers Last reply
More about giga machine wont boot power cycles
  1. Do you have a power supply to swap and test? I have seen a similar issue and it just turned out to be that not all the power cables to the mobo/gpu were seated correctly, so that's one thing to check real quick.
  2. Yes. Read the stickies at the top of this forum.
  3. Thanks - reading stickies now (first time on this forum)

    Tried with PSU and CPU only connected and same behaviour.

    A short or faulty PSU seem most likely.

    I'll have to try and source another PSU
  4. I tried another PSU - no change.
    Tried taking MB out of case - no change.

    The only change is if I connect the ATX cable the LEDs and power stay on for longer - maybe one second, instead of going off almost instantly.

    Any more ideas out there?
  5. SOLVED.....

    by loosening CPU cooler screws (Thermalright Ultra 120 with backing plate)
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