Power Issue on a new PC

Hi folks,

Struggling with a bizarre power issue on a very new PC which has got me stumped.

Spec:

i5 6500
2x 4GB Corsair Vengenace LPX DDR4-2133
250 GB Samsung Evo SSD
R9 390
Gigabyte H170-D3HP
550w EVGA SuperNova GS

PC was built end of January with no problems and has been running like a dream until this morning. Machine powered on, bios screen showed and then there was a clicking noise and the machine shut itself off and back on again. It stayed on for a few more seconds before again clicking and turning off. It turned itself back on again and stayed on but with no source on the monitor. I powered off the machine and after that point the machine did not react to the power button being pushed. The graphics card light and network lights were both still functioning. After coming back to it this evening and press power on it repeated the exact same cycle as above and for a period of about 15 minutes didn't respond to the power button.

I have disconnected everything so that there is just the cpu, cpu fan and psu and the power and hdmi cables and the machine is powering on more consistantly now but still no source with onboard video. On power on it seems to be again turning itself off after a few seconds and then starting up again and staying powered on only on that second attempt.

I have also taken the CMOS battery out, disconnected all the power cables and re-attached them, and checked all the other cables to ensure they are connected with no resoloution.

Is the clicking noise still present? And did you find where it came from? I seem to recall some PCs won't start if a fan is obstructed, so that may be one place to look when you turn it on.

Apart from taking the battery out, if your mobo has a reset button or jumper, activate that as well. And finally, maybe try another PSU if you suspect a power problem?

Thanks for the suggestions. Clicking noise seems to be coming from the PSU and occurs at the moment the machine powers off. All three fans are unobstructed and running fine. Sadly I don't have a spare PSU, but with my luck it might be a wise investment. PC powers on when using the jumper with no power off and on cycle but again with no source.

Some power supplies, especially newer ones, have a relay to bypass the inrush resistor and improve efficiency - it could be this you're hearing if it's just a single click when the power is switched off?

Yeh it is just the single click when the PC turns itself off. I guess I'm looking at RMAing the PSU or the Motherboard, leaning towards the motherboard with it not displaying and the fact it still seems to have power. Just hesitant to jump right in and a week later Scan reject it and send it back saying its passed their tests.

If you got the lot from Scan, get in touch and see what they say as they might take the lot back and test if for you. Or if you live close enough you could drop it in.

I will post in their after sales forum and see what they say. Thanks for the assistance.

For closure I just thought Id let you know that the motherboard turned out to be faulty. Scan gave me a direct replacement and seems to be working fine now.