Is it the cpu or the motherboard?

[sexydad]

Hello, I'm wondering whether the motherboard or the cpu is dead. I tried to install a hard drive and a floppy drive to a biostar motherboard (G31M7TE ver.6.0). In any case, upon installing the hard drive and floppy to the motherboard I powered the computer on using an ATX 460W power supply; the only things that turned on was the cpu fan and the system fan. I attempted to turn the computer off via the power button and could not do so. Is the problem with the cpu or is it the motherboard?

 

[Herr_Koos]

Is the motherboard power LED on?