Everytime i turn it on i can hear the fans starting my leds are glowing and such. But after 3-5secs it dies right off. Then without me pressing anything it starts up again after 1-3secs.
Normally it boots after one time of this procedure, but sometimes it does it 4 even 5 times.
Also notice that it does it atleast once every time i start my computer up, and that the screen doesnt turn itself on.
then the suspect is the PSU because i've resetted it like 100 times trough out my years of this computer. And it's still the same. Always has been, always will be
I had almost the exact same issue with one of my computers, and in the end it was just the Mobo dying... (though it was a crappy board from the get-go based on the 680i chipset... those p35s are "usually" pretty stable).
Something is going bad, or went bad, and order of 'most likely' would be the mobo, then memory, then... anything else.
(I'm sure you've already reseated all of the connections, just for f*cks sake, heh)
Borrow a friend's memory stick and try just theirs, or buy some RAM at a store than has a return policy... try it.
Maybe try another vid card?
If none of those fix it, get a new mobo (you could get a p45, which would be pretty awesome)