My PC (modest, not self-build) starts only intermittently - about 1 time in 10 is successful. It seems more likely to be successful when it has been off for 30 mins or more. When it fails (most of the time) this is what happens. I push ON, the fans start instantaneously, the red LED on motherboard stays alight and the green LEDs flash for fraction of a second, keyboard lights flash, then everything dies. The whole cycle takes less than a second. Red LED on motherboard stays on, everything else off. It will not respond to the ON switch again until I disconnect the power and red LED fades. I've cleaned out all the dust, checked the internal plug seatings and tried with floppy disconnected, so far. Can anybody help me with where to focus (I'm not an expert)? Thanks ...