Ok... lol
My pc is not happy

I will press the button and it wont turn on, instead the fans and lights will come on for a split second and then die. I replaced the power supply from a 500watt to a 700 watt, and ive reseated everything and checked connections. Now, strangely enough, i managed to get into windows once, completly randomly,so that leaves me to believe that my hd and mobo are not dead... which i hope there not. Anyone have any ideas? Something obvious, or a way to check this. Help please!

Just to verify:

Both PSU's result in the same behavior?

Was everything fine at some point then it suddenly started acting like this?

Any possible hardware changes coinciding with the problem?

My first thought would be a short of some kind.

What power leads are you using besides the main 24/20 pin and the 12v 4/8 pin? Any Sli power leads?