TriggerFinger

I hope you know what you are doing... doing checks on-board might be harmful to you and your system if you make a mistake. That is also the reason why I stay away from on-board repairs.

Going back on the RAM... if you know a friend who has a laptop that accepts the same type of RAM, you can test your RAM sticks there. With that out of the way, you can focus on other things make it a bit LESS complicated.

About the video card. I really doubt if there is an on-board video controller aside from the 2 video cards that you have. My guess is, the reason why it is powering ON with video cards removed is because the mobo provides power to the screen but that is all there is to it.

It is rather complicated because we do not have the parts to use in our isolation. If only you have another laptop similar in model that you can use to test the components of the other then things would be a little clearer.