Gigabyte P55-US3L stuck in reset-cycle

[GAteKeeper]

I have bought a set of core i5 bits including the above P55-US3L motherboard and after inital setup and configuration it is now stuck in a reset/boot-cycle of ~3seconds on/off and nothing appears to reset the bios (suspect dodgy ram settings).

All of the following tried with minial bits plugged in (PSU 24+4 +12V, RAM and gfx only)

1. Tried RAM in another PC - posted fine
2. Tried different RAM in this mobo
- Tried the ram in all slots
3. Tried a different gfx card (known working)
4. Tried gfx card in another machine - posts fine
5. Tried resetting bios
- Removing battery + PSU + shorting CMOS pins
6. Holding down Power button for > 4secs
7. left it resetting for 10mins+ and no change

I dont have a way of proving the CPU but I dont think its the CPU.

Open to suggestions otherwise RMA please.

GK

[LuckyNV]

What RAM did you buy, what USB devices do you have attached?

[GAteKeeper]

Corsair 4GB (2x2) XMS3 DDR3, PC3-12800 (1600), 240 Pin, Non-ECC Unbuffered, CAS 9-9-9-24, XMP
and no USB

[rabbid]

check for shorts
check cables secured (pull out put back each one to be sure)
run isolated with minimum components to see if you can achieve a POST.
even try another hdd or boot from cdrom with no hdd attached or vice versa

If no success then you need to test cpu in another board and/or another cpu in your board

[MaddAussie]

Yeah I had a similar problem many moons ago, it turned out to be a cable from the reset button that was shorting took ages to track iy down, a bit of insulation tape later it was sorted

[GAteKeeper]

I have it out of the case at the moment, nothing but CPU and HSF + PSU, using a screwdriver to start it, still doing it.

As its my first i5 I dont have a spare CPU/M'Board to try to eliminate the failure.

GK

[jim]

If you bought them all from Scan, then I'd recommend sending it all back together - CPU, PSU and motherboard. I had exactly the same problem, and everybody told me it almost certainly couldn't be the processor, but it turned out it was.

I only found out because Scan tested them all simultaneously until they found the faulty part - you don't pay Not-Found-Faulty fees as long as one of the parts you send back is bust.

EDIT: Sorry, didn't see it was After Sales forum, came via new posts. Will leave post as is for now seeing as it should be useful.