Computer on then off then on etc.

[zachcuden]

Hey guys I just helped my friend move his computer parts from an old case to a new case. He had a dell xps 8000 but had replaced the ram with ripsaw and it was working perfectly. Then in replacing the case we also changed the psu to 780w and added another harddrive. We have tried so many things to get it to work. We have tried unplugging each thing and that didn't work. We tried the old power supply and same result. The only thing I can think of is either we somehow damaged the motherboard while moving it or that there is something wrong with the power button. We tried doing the CMOS reset, but that just made the symptoms start when flipping the psu switch instead of after pressing the power button. If I hold the power button for 10 seconds it will stop going on and off. But once I do anything like unplug and replug then it does it again. It's only on for about 1-3 seconds at a time and off for about the same amount of time. Any help would be much appreciated. Thanks!

Found out it was missing a 4 pin plug. Just found it and voila

Parts:
Cpu: i5
Ram: 8gb RipJaw
GPU: nvidia 220
PSU: xpower 780
case: coolermaster black 430 elite.

 

[bryonhowley]

First thing I would check is to make sure there are no mainboard standoffs shorting the board. To me it sounds like a short so that would be the place to start. The best thing at this point would be to remove all components check the standoffs make sure they all match with the screw holes on the mainboard.

After that install just the mainboard (with the cpu and ram still attached) power cables for main board and Video card plus power for Video card. And front panel connectors for power switch. Leave hard drives and optical drives off for now. If your system powers on then you can start adding the rest of the hardware.

 

[zachcuden]

Best answer selected by zachcuden.