Nothing else connected or plugged in.
If that fails move the mobo to a piece of cardboard....test
If that fails your down to 3 parts.
My computer turns on for a spilt second and then turns off. The video card, all the fans turn on as well and then it just does this in a repeated cycle. Turns on with all the things above and off then and off. I was thinking it was the PSU, but I have a spare and switched it out and even the cable to the PSU and same thing is happening. Any ideas?