Xfx radeon hd 5770

Solution
No not at all with one card it is running in 16x mode it is only in crossfire mode that it drops to 8x8 but HD5770 will not notice.
OK I fixed my link above so you can see the specification now. It is a true crossfire board but runs the cards in 8x8 configuration but a single card in 16x. If you get a FX chip-set board it will run crossfire in 16x16.
It is only the most powerful GPU's like HD5970 that get affected by running on 8x lanes.