Mario Kart Wii Multiplayer Dolphin 3.0

[haddockd]

I have read before that multiplayer is more intensive. The more players, the bigger the hit. If memory serves (and I may be wrong on this), it increases GPU load more than CPU load. Since you have a 6950, have you considered BIOS modding it to a 6970? I did and it made a world of difference across the board in dolphin.
If you are interested (and you assume all responsibility):
http://www.techpowerup.com/articles/overclocking/159

I am not in front of my home PC so I cannot comment on my exact settings unfortunately.