New Giga i5 machine wont boot - power cycles

[ronslam]

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

 

[boonality]

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.

 

[jitpublisher]

Yes. Read the stickies at the top of this forum.

 

[ronslam]

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

 

[ronslam]

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?

 

[ronslam]

SOLVED.....

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