Have you tried just the processor, no RAM, vid etc...? It should at least beep at you then. Do you have an old MOBO you can put your processor & RAM into to check those (sounds like you don't)?

Is there perhaps a loose case screw sitting where it shouldn't (give it the shake test)? Does the mobo/proc/RAM operate with the case mounting screws removed (perhaps a cold solder joing that flexed open)?

-Zeke