I understand that you are inquiring about the compatibility with some video cards that do not use all the contacts on the PCI Express* 16c slot.
In regards to your inquire, the amount of contacts on the video card is a design difference and Intel(R) will validate this. Sometimes video card manufacturers will simulate the video card as being x16 when they are internally 8x. Then again, this is compatible and should not affect.
What is the advantage of this? Is this done because it's a cheaper solution?
I will say that (from my perspective) the DQ45CB seems to have obvious issues with alot of these type of cards.