Crossfire of ATI Radeon HD 3870

[HawkEye1]

I have a crossfire of HD3870 paired with a E8400, 8GB of RAM all on Vista Ulti 64 without any particular worries.
I play Warhammer online in 1280/1024 with almost all effects, but the game is not supposed to be greedy.
I have, through the catalyst, placed at 4x Aniso and 4x antialiasing option with time.
I turn to 55/60 fps.
A friend has just set up a 1GB version HD4870 on a E8500, and on the same games, with the same effects, it runs at 90fps max in a resolution much greater.

I know that 3870 is the less powerful of course, but how is it that I do not even exceed the 62 fps?
Are there one or more individuals to do tests to see if there is a problem or is this normal (which I do not)?

Thank you for your help

[need Tos]

We must tell you that a crossfire in 3870 is roughly a 4870 512mb.

As against the anti-aliasing is very poor support, does not seek further

[opaper]

update you drivers? ( PCI Express 16X for 2 or 8X-8X or 4X-16X i think )
I said no oc CPU limited but it would have been at least around 100-150 fps with this process (although this game may be monot read)

And worse is playable 60fps

[HawkEye1]

For info, just 30% of my ram used, and the two cpu does not exceed 70/80% in sub max Warhammer.