No boot no video

I am rebuilding my PC. Replaced old motherboard with new identical one. replaced video card and harddrive.

At one point I had video and was booting to a cd. Now I have nothing after formating harddrive.

Lights are on for motherboard but keyboard, mouse and monitor do not seem to be on.

Only thing I have not replace is Pwr Supply. How can I check to make sure it is supplying proper voltage. I haave already removed all non-essential pwred components.

I have a multi-meter and not afraid to use it