Here is a new troubleshoot I have.
I just got in SLI now and spotted on slizone you can have some kind of "SLI AntiAliasing",
especially designed for dual video cards.
I then walked on Nvidia control panel,
put SLI 16x to give a try and in ArmA it gave nothing, no AA.
I tried disabled ArmA AA (maybe bad overriding) but it didn't work.
I removed it back to "application controlled",
then had nothing at all !
I replaced ArmA AA and didn't work more.
I tried again, back, etc and finally had SLI 16xAA to work.
It was really AA'ed, but 5 fps wasn't enough for me on Rahmadi,
so I put it back to "automatic".
Since, no way to have AA in ArmA. What's the matter ?
Edit: I tried in single-card mode (via game profile, and disabling SLI too), no more AA.
There is no override setting in default NVidia profile.
Did I do anything wrong ?