[Carbon]

If it comes *right* on after you hit the power button, it's probably just going into hibernation.

If not, overheat/psu issue.

[delboy2028]

maybe but like i said it acts as if i pulled to power plug from the back of the psu and then turned it bk on.

requires no waiting time or nothing before turning on

[Eltocliousus]

It could be a number of things, hard for the community to help you with.
I had the same problem with my old HP and a few months ago i found out the problem.

Basicly all it had been was a faulty power switch on the power supply.
Thats the problem, little things like this can be the Culprit.

[cheesepuff]

did you OC at all? if you did a bad OC that will happen. the computer turns off to save itself from dying.

[delboy2028]

i dont oc but

eltoc i just noticed my power switch on my psu dont work ne more guess the problem is found wen i get some ££ i will get the psu nd report bk it may help others

[kanoakavirus]

Could be somthing as simple as the power cable my monitor cable and my psu cable are the same , if this is the same for you try simply changing them around sounds simple but i once took my ps2 apart because it wouldnt turn on and later found out it was just the fuse in the plug... anyways back to your question as cew27 said i doubt anyone could pin point the problem but id put my money on the psu , when your comp turns off completely is there any flashing lights on your tower? like dvd drive

[kanoakavirus]

ps if your able to change the monitor and psu power cable around and fine your monitor turns off but your tower stays on then you know its the cable simple i know but not impossible