My brother's computer has developed an interesting condition. If you press the power button, the fans whirr, and the power light turns on for a split second, and then stop and the computer lies inert. No matter how many times you press the power or reset button after that, it won't turn on or do anything, until you turn the power off at the wall and wait for the motherboard power indicator light to turn off. Nothing really unusual about that, I've had several other computers with that sort of problem. However, if instead of just pressing the button, you hold the power button down - even if just for a second or two - the computer turns on normally and works with no other problems, that I've seen so far. Any ideas what might cause this? It's not a huge problem, because as I say, the computer works fine... but I'd like to get to the bottom of it. I'm guessing it must be something to do with the motherboard itself... as the power supply can clearly supply the power, and the switch doesn't seem to have a problem making a connection or anything. Tis odd. There are no diagnostic lights or anything on the motherboard, it's not a particularly fancy one.
I'd take a stab at either upgrading or reflashing the BIOS.. After trying the usual "set everything back to el boggo defaults"
Whats happening is the PSU is not holding its 'turn on signal' Normally when the Power Switch is pressed, a signal is sent to the PSU to turn on. It only turns off if told to do so. By the sound of it, the PSU needs a few seconds to stabilize its 'Turn on' signal & stay on. It could be a motherboard fault, which holds the 'On signal' in place. So, i would say its probably two things, either a faulty motherboard or fault PSU.
I generally find this kinda of issue to be PSU. It could also be mobo, but PSU is first place to look. Also if you have access to a multimeter, check the chassis is ground correctly (measure resistance to earth, should be 0 ohms)
