Does the green light on my p5k-e motherboard mean it is working?

My power went out and my computer wouldn't turn on at all. Now that I bought a new PSU it only comes on for 2 seconds then shuts right off, what could be the problem? When I say turn on "most" of the fans come on but not all.. My motherboards green light is on does that mean it is working so I don't have to buy a new motherboard? I have an ASUS P5K LGA 775 Intel P35 ATX Intel Motherboard. Could it be my RAM or CPU?