I just got my second 5870 for crossfire, and the only game so far that i've seen an increase is crysis 1.
Every other game i have is 10 FPS more at most.
GPU usage in alot of my games is around 30-45%.
Even crysis 2, the only difference between one and two cards was flickering.
Games i tried
Call of Duty 4 ~ 190FPS (slight increase)
Call of Duty Black Ops ~ Gets around 100FPS (no increase)
BF: Bad Company 2 ~ 80 FPS (no increase)
Crysis - ~60FPS (major increase)
Crysis 2 ~ 80FPS (no increase)
GTA4 ~ 40-50FPS (no increase)
In crysis 1, i can manage very high settings @ 1680x1050 between 55 and 80 FPS on the beach. (depending where you're looking at)
EDIT*
Using 11.4 Preview drivers
Every other game i have is 10 FPS more at most.
GPU usage in alot of my games is around 30-45%.
Even crysis 2, the only difference between one and two cards was flickering.
Games i tried
Call of Duty 4 ~ 190FPS (slight increase)
Call of Duty Black Ops ~ Gets around 100FPS (no increase)
BF: Bad Company 2 ~ 80 FPS (no increase)
Crysis - ~60FPS (major increase)
Crysis 2 ~ 80FPS (no increase)
GTA4 ~ 40-50FPS (no increase)
In crysis 1, i can manage very high settings @ 1680x1050 between 55 and 80 FPS on the beach. (depending where you're looking at)
EDIT*
Using 11.4 Preview drivers