I know this is a dead thread but I wanted to confirm Ferrai's advice worked for me for any future readers.
I had similar PC issues like the OP, only the GPU and CPU were powered of which by fans were working.
Everything else was not, computer wouldn't beep or get past post. There would be no signal on screen, mouse, keyboard and DVD drives were dead.
Following Ferrai's advice for CMOs removal and the advice listed on other forums I removed the CMOS battery for about one minute and put it back there after.
Whilst the battery was unplugged, I then removed the RAM sticks and sprayed the sockets with compressed air. From there I switched the RAM sticks around so what was my #1 RAM was then placed in the socket where its sibling lived and vice versa.
I powered up the machine with just GPU, CPU and 1 stick of RAM connected. Some how I got post. Turned machine off and placed 2nd stick of RAM in machine - again got post and repeated the last step adding another bit of hardware as I went - HDD, HDD2, DVD drive etc. In the end the whole computer was reconnected and managed to get back up and running.
When windows was loaded my volume slider and network icon was missing, but in the end this rectified itself by restarting.
For me it was not a PSU or Mobo issue (thank god). I'm not sure what it was exactly but the 2 methods above saved me big time. Thanks Ferrai.
PS this is a throwaway account. Good luck to you in the future.
Edited by nomorebeeps, 23 May 2013 - 04:09 AM.