Stoopid Question for you all, sorry in advance.

Depending on the chipset and the motherboard, some boards only have 16 total lanes to work with. So if you run one card, you use x16. If running two, it splits the load to x8 each. Techically the x8 could bottleneck your cards, and in reality it will decrease SLI/Crossfire performance slightly. For a new build I wouldn't recommend starting with Crossfire/SLI. Buy one more powerful card now rather than two kinda powerful cards, then you can add another card later to get more performance if necessary. You can save a lot of money that way.

Personally I only entertain x16 + x16 motherboards in my SLi rigs.

At this point, you won't notice much of a hit from x8/x8 at all, though if you add a third or fourth card running x8 bandwidth then you will basically lose all your advantage. Today, it doesn't matter. However tomorrow might be different, I am personally waiting to see how 2 of the various 5xxx series GPUs scale on i5 with its x8/x8 bandwidth before saying either way.

In all honesty, I have used both and I find that the difference is overhyped and hard to judge because you ARE changing parts of the system, meaning any benchmark is not up to scientific standards because more than 1 variable has changed.

No, not at all. It is safe to assume that if it doesn't say x16/x16 or x8/x8 then it is NOT x16/x16, but likely x16/x8, x16/x4, x8/x8, x8/x4 or something even worse. If you must, look up reviews and the board on the manufacturer's actual site for more information.