I was looking at getting a Gigabyte z68 mobo for my new board. While reading up on it I saw that it says one gpu will run at 16X speed. In crossfire mode though one card will run at 16x and the other will automatically default to 8X even though its in a 16Xpcie slot. So my question is how much of a difference does that make. Its 50% slower so whats the point of using crossfire if one card is running at 8x speed and the other at 16X. Also is that 8x default on all mobo's using a crossfire config or just z68's?