Comp dead...Mobo? [ASUS P5N-E SLI]

Wasn't sure where to post this but any ideas/comments would be greatly appreciated!

Rundown of the situation...came home last thursday night to find comp dead. I had left it on when I went to work. Wouldn't power up and nothing I could do as far as plugging/unplugging/trying different things would get so much as a noise or light from the machine. Figured it was the PSU so I ordered a new one.

After I installed the new PSU today the first time I put the power cord in it gave a little noise and the fan acted like it wanted to move then it promptly died. I unplugged it for a bit and then replugged it back in and it powered up. Heard some random beeps from the mobo but it seemed to work so I shut it down and took it upstairs to hook up the monitor and everything else. It powered up fine again but my rear USB ports didn't work (wouldn't recognize my mouse) so I shut it down to put the new RAM in. Since then it won't power back on anymore. If I unplug the cord or switch the PSU off for a little bit and let the charge go away when I put the power back to it the neon light on the bottom of the case will light up for a split second and there is a click as the rear case fan tries to spin and then it all dies again and I can't get any response unless I unplug for awhile and then only get the half second of light and fan noise.

Mobo is an ASUS P5N-E SLI, Dual Core E6600 CPU, XFX GeForce 9800GT, 2/4/or 6 gb of GSkill 800mhz ram, and the new PSU is a 700watt Raidmax.