ARMA 2 OA crossfire and -winxp switch help

[toscar12 1]

hi i have been having trouble with my crossfire set up as it shows no improvement over one card in arma 2 oa. So i found a couple of testimonies from people who have used something called -winxp switch? can anybody help by telling me what this is and how i give it a try?

---------- Post added at 03:45 ---------- Previous post was at 01:58 ----------

Well i found out its a launch command but it doesn't seem to make a bit of difference does anyone one else know and fix or workaround for arma 2 oa crossfire performance or scaling