when power supply is plugged in =/
What? What do you mean?
my pc just starts up automatically.. when i plug in the power supply.. the fan will be running and so on but theres nothing showing on my monitor. i have to unplug the power cord to shut it off.
Unfortunately that is usually a sign of a dead motherboard. A short in the motherboard will oftain send the on signal to the powersupply even tough the powerbutton has not been pressed.