When power button is pressed, the pc starts up and will run for a moment or two-sometimes right through to windows but mostly only for a couple of seconds or so-when it shuts down it will start up again without intervention and may just stop and start continuously. I changed the psu with all drives disconnected. Same problem. I changed the motherboard and system ram and cpu and fan. Same problem. However I then discovered that if I start up the power by momentarily shorting out the two pins which the case power button lead is normally connected to everything works ok. There does not seem to be a short or identifiable fault with the pair of wires which connect the case start button to the m/board. I am completely stumped with this one! The logical answer seems to be the system case somewhere but I cannot see why.
Any ideas?
