Computer keeps turning itself on

[Lysander]

Weird one, one of our computers keeps randomly turning itself on. I opened it up, took it apart, cleaned it [a LOT of dust] and it was fine for a bit then -beep- on it goes again.

Weird, what could be causing this?

 

[Lysander]

E6600
2GB ddr2
x1950pro

Some old asus motherboard

Well, it turns on, not off. No BSODs or anything like that. It actually boots itself up when it starts.

 

[Lysander]

Not from sleep mode, from actual shutdown.

Yeah, I'll check the front panel. Really odd though. If it was from sleep I could understand but this is when it's off.