Hi, My 4 year old Gateway desktop is on 24/7, then one day I got home and it was off. I tried starting it, but only the on light came on. I tried a new power source, then a another mother board, but still nothing. There is a light on the mother board that illuminates when the computer is plugged in. When I hit the start switch the light comes on but nothing happens, if I press and hold the switch the light goes out after a few moments as it would once the computer would have shut down. I've checked and rechecked the connections, I don't see any obvious problems. Do you have any ideas? My last option is to bring it somewhere because of the expense just to bring it in. Thanks.