Computer won't start up, details and troubleshooting explained...?

[DarkWolf_1st]

My computer died last week. I thought it was the cpu so I bought a new one, but it didn't work. When I start up, the lights go on, the fans start spinning, but that's it. I don't get a POST or a Beep or anything. The cpu light does not flicker or go on. I switched it out with a spare motherboard that I had and a spare cpu I found. Nothing happened with each motherboard with each cpu. I finally decided it has to be the power supply. How can i check the power supply?? Is there a way to check the individuals pins at the connection to the motherboard?? Is there a way to check the pins on the motherboard as well? I just bought 2 gigz of RAM and a TV tuner card so I have to salavage this computer =(
Everytime I tried booting up after switching the motherboard, I only had the CPU, motherboard, a stick of RAM, and the hard drive put together. I've taken oput my video & sound cards as well as my other 3 sticks of RAM and my DVD drives. Won't putting a paperclip on the connection short out the battery?? 0_o