[QUOTE=eric93se;2469545]You might have to clear the cmos on the MB to get it to boot.[/QUOTE]
Excellent advice and if that does not work unplug all leads and take out any other cards other than the graphics. carefully re-seat all leads and do the same to the memory. Is the cpu mounted correctly? check and make sure that all is well and switch on.
Still not working? then disconnect all other units, hard drive cd/dvd drive etc until you have a bare bones system turn on and see if it will at least show the bios warning of no drive etc. if it works turn off and add the hard drive and turn on keep adding units until it stops. Investigate why.
If none of this works can you try a different power unit, if still no joy then the mb, cpu or memory could be faulty.
Its a matter of elimination, good luck.