Ok I have this problem for the last 2 years since I upgraded the bios for my P55WB.
My PC boot by itself for no reason!
I thought like some people told me that it's the PSU but I changed it last week with a brand new XFX,so it's not the PSU.
Some people told me that perhaps the PC's case power button is broken or something,I replaced the case as well with a new Thermaltake.
Another option was to disable wake on LAN but right now I don't have any network cable plugged nor wake on Lan ON.
So it's obviously the motherboard!
I upgraded to the latest bios but still no joy.
I even changed my graphic card but the problem was still here.
So how can I fix this damn problem??boot start