There is a green light on my motherboard

It means that standby power is available. It doesn't mean that the motherboard works or that the power switch is connected correctly.

Ok, I've confirmed that the power switch is connected properly and it does work ( tried it on a different computer), i unplugged and reseated everything. I still have the green standby light on the motherboard how can i test the cpu? and what else should i check that is relatively easy to check while i'm at it?

There's a sticky on Tom's that could be helpful: http://www.tomshardware.com/forum/261145-31-read-postin...

You can test the CPU in another system or bring it to a shop and have them test it. Based on your motherboard, I presume that your system is a few years old.

The LED means that the small, always on standby power supply in the PSU is working. Basically, all it tells you is that the PSU is plugged into a live wall socket and the PSU is turned on. It has little to do with the circuits that provide operating power to the computer.

The bare minimum you need to (sort of) test the CPU is a motherboard, CPU & HSF, PSU, internal speaker, and a way to turn on the the computer.

If the PSU, motherboard, and CPU are working, you should hear a continuous series of long single beeps.