Crossfire setup supposedly improving FPS, but not really?

Hi, this is a really strange problem I just noticed I had now. I've had 2 4870s running in Crossfire for about a year now. I decided to play some Crysis, and I forgot to enable Crossfire. My Crysis settings are 1900x1200, no AA, and all settings set to VERY HIGH. While playing the game I instantly noticed that I was getting around 24 FPS, which is lower than I remembered. So I quit and enabled Crossfire in CCC, and ran Crysis again.

This time I was getting around 38 FPS average, in the same area of the game, but the frame rate did not feel smooth at all. It actually felt smoother playing with one card. Has anyone else heard of this kind of problem? Is FRAPS reporting the incorrect frame rate? I also checked and I didn't have v-sync enabled.

Team Fortress 2 runs at a constant 60+ FPS with everything maxed out, 8x AA, 16x AF, so maybe this is just an issue with Crysis? I'm also getting around 40 FPS in the Crysis 2 demo at Gamer level, which is supposed to be the lowest setting, but 30 FPS at Hardcore.


My other specs are:

i5-750 stock
4 GB DDR3 RAM

and I have the latest graphics drivers.