Motherboard Problem

I've just finished building a computer for my friend and the process is complete. However, when I go to boot up the computer nothing happens. The only sign of power is that the processor fan moves slightly. Could this be a motherboard problem (ECS KT600-A), a processor (sempron 2400) motherboard malfunction, or a power supply problem? I've hooked the computer up to a different power supply and the same thing happens. Any Ideas?

 

this sounds stupid but it happended to me once, make sure that you don't have your 12v line plugged in backwards to your m/b ( it will fit both ways-well atleast it does on my mother board )

 

As an addition to what Mellowman said (I still don't know how he managed to do that...lol), check the picture of this PSU tester, what I want you to pay attention is the square shaped 12V connection in the middle, if your mobo has one, then you must have a power cable plugged in that connector as well so the CPU gets its juice. The other possibilities:
~ incorrect case cable connections (the cables coming from the front of the PC case and plug in on the mobo.
~ CPU 's gone bye bye!

 

Make sure the jumper to clear cmos is on pins1&2 and not on pins 2&3

This can cause that problem, I have forgot to move it already and thats exactly what happened.

Rick