- Remove one of the RAM sticks out and turn on your PC if this didn't work then continue removing another one. (could be a faulty RAM)
- Make sure your power supply cable is enough to power the PSU. (Amps & Volts)
(Try changing the cable)
- Check your CPU to see if its overheating (change the cpu if all else fails)
- Remove the Bios battery and leave it for at least 3 minutes and plug it back again.
- Try switching the video card with another one (Maybe old spare one that you have)
- Switch the entire Power supply with another one
If none of these solutions worked for you then i'm afraid that the problem is the Motherboard
Let's hope its not.
Best of luck!