PC wont turn on if left plugged in

[MJM78]

Hi guys
Got a strange problem with my PC
If I shut it down then turn it off at the wall when I turn it back on all is good, but if I shut it down and leave plug socket turned on at wall (PC still off) when I try to turn on computer I get nothing, at all, just completely dead, I then have to turn it off at wall and leave it several hours. Seems like PC is still drawing power from socket whilst switched off and a capacitors overcharging or something?? With my limited knowledge. Guessing its either PSU or mobo at fault but no idea which, both appear OK, and as I say there are never any issues with starting as long as I remember to turn plugs off at wall. Had PC about 2 years, and this has just developed over last 6 months. Tried replacing mobo battery in case that was somehow at fault (cant see how it would have been but it was an easy fix) no joy.

Mobo is an Asrock Z68 Extreme4 Gen3 Intel Z68
PSU is Corsair AX750
single 580 gfx card

Hope someone can help

 

[stulid]

Does the PSU switch on correctly? Google the "PSU paper clip" test and see if it turns on and off when you replicate what the power button should do when you press it on the case.

If that works ok, then it leaves just the motherboard at fault.

 

[toon_mad]

If I shut it down then turn it off at the wall when I turn it back on all is good, but if I shut it down and leave plug socket turned on at wall (PC still off) when I try to turn on computer I get nothing

When it is still plugged in at the wall with the PC off does the motherboard have leds anywhere that are lit up (usually there might be one led somewhere) to show there is power going through to the motherboard?

 

[MJM78]

No theres no LEDs on mobo when its all off so no way to tell

Re paperclip test, I presume I'll have to try that when I next forget to turn it off at wall n it doesnt turn on normally, as I'm sure it'd work now with it all being OK atm, thanks for suggestion

 

[stulid]

Do it whenever.

You pull the power connectors out of the board, grab the bigger 24pin connector and simply short the green with a black wire, this is what pressing the power button on the case does.

The PSU should switch ON which is normal behaviour, if it doesn't then that could be the faulty part.

 

[toon_mad]

Following on from what stulid said you can buy a PSU bridge connector for a few quid if you are not comfortable using the paperclip trick. Basically it clips onto the 24pin connection and has the necessary wires to effectively jump start the PSU (if that's the correct wording)