Crossfire Performance Issues

First my system specs:

AMD FX-57
Asus A8R32-MVP (Bios 0404, though same issue on 0311)
ATI X1900 XTX
ATI X1900 Crossfire
2Gb OCZ PC3200 Platinum
Audigy 2ZS
NEC 20WGX 1680x1050 @ 60Hz
Windows XP SP2, .Net 2.0
700W FSP Power supply, Crossfire Certified

When I run Oblivion, I see a huge increase in framerates when running in Crossfire mode, it's amazing. But when I run CoD2, Tomb Raider Legend, Rise of Nations: Rise of Legends (Demo) or Ghost Recon Advanced Warfighter (Demo) I see no difference in my framerates between Crossfire and single card mode. I'm using fraps to record framerates. I might see 1 or 2 fps difference, but I think I should be seeing a much higher increase in my frames per second with a Crossfire setup. I know that Oblivion has an AFR profile, not sure on the others. Even if they don't have one though, either the supertiling or the scissors mode should be in effect and giving me a performance increase. I'm not seeing any. I've tested this with both AA enabled and disabled, not going above 6x as I realize this enables SSAA and disables any performance increase in Crossfire mode. Am I missing something here? Can anyone possibly explain why I am not seeing any benefit to having Crossfire with any of these other games? I know it doesn't make much difference at lower resolutions, but isn't 1680x1050 high enough that I should be seeing some performance increase? 3DMark06 shows a 2000-3000 frame rate increase. Between Oblivion and 3DMark06, I’m sure Crossfire is working and that I have things configured correctly. Can anyone possibly shed any light as why I don’t see any difference in other games, or what I need to do in order to see a difference?