I am currently helping my brother out and we are having the same problems. I have even took out all of my spec except my motherboard and still nothing. I have tried everything!!!
I thought it could be his RAM But I plugged mine in and nothing. I will explain what we have done.
We have tried 3 different graphics cards (including mine) - Nothing
We have tried each stick of RAM, then tried mine - Nothing
He has a 900w PSU, Mine 650W tried both - Nothing
Tried resetting COMOS - Nothing
Changed VGA cable DVI Adapter - Nothing
Tried my monitor with my VGA - Nothing
We still cannot get it to work and like you said everything is connected up properly and power going to everything he has for his build.
He has done exactly what you have done. Bought a bundle pack and nothing has responded. If you find out what has happened update me
We are getting a friend to look at it so if we find out the problem I will give you an update. He should know what he is doing hes a games designer for EA Sports