Ok its about time I had something to complain about with my pc again. It's an odd one, so bear with me

First started maybe a month ago. I was leaving my pc on some nights to do afk selling on an online game. On switching it off in a morning, sometimes it would actually restart. Properly, as if I'd pressed 'Restart' in the windows menu, so windows would shut down, then start up again immediately. I put this down to possibly overheating, i.e. its been on all night and then 'waking' it up with the mouse activity was causing overheating just as it shut down.

Then it started doing it at random. Once my pc had only been on for 10 mins for a quick internet round before work. And finally today, the last straw. I switched it off before going to work. A good 2 minutes in advance. As I walked out the door, the screen was black, no lights on the tower and no noises coming from it to indicate anything was going on. 5 hours later, I get home... and the pc is on. (yes, the door was locked, no mole hadn't been home )

I've checked for viruses (updated whenever available, scan every thursday), and carried out an adaware check for spyware etc. Everything is clean except the odd tracking cookie that you pick up. I've had no hardware changes since September, no environment changes, nothing except the odd game being installed.

ok, your problem is hardware. That's it, no doubt, nothing else. Nothing in software can cause a computer that is completely shut down to start up. Why? Because there is no software. You can't run any problems with no power to the RAM.

What you've probably got is either a bad power supply or a fault in the motherboard, or a fault in the front-panel wiring. You have an ATX power supply (I'm certain), which means you have a soft power supply. IE, in old computer, you hit the power button and physical power was interrupted to the system. The circuit for main power was opened so nothing can flow.

Not so with ATX. With atx an electronic signal is sent to the power supply (I believe) which then stops all but some trickle power into the motherboard. When you hit the power button, another signal is sent to the power supply to reactivate main power. IE...rather than being a physical circuit, it's hardwired logic.

Hence why it might be the power supply. Anything else involved in that loop could also be at fault, but I'm rooting strongly for your power supply being bad. Otherwise, it could be the front panel connectors (ie, they short and thus 'think' you pushed power) or your motherboard is flaking.

Yay me. Try swapping power supplies with Mole's computer and see if the issue keeps happening.

ok i'll try it, however I always shut down using the windows start/shut down thingy, i never touch the power button on the tower except to switch the thing on, so does that make any difference to what you said? (electrics are far too confusing for me )

heh, no, makes no difference.