Hi i've got Q6600, QX6800 and QX9650 on stock speeds atm for stability before I upgrade to 8350 next week.
I've been playing Arma 2 with old 9800 GX2 for a good while and was even able to record videos for youtube with around 20-25 fps left for me. Nothing impressive ofc
So I upgraded to GTX 670 and I am playing DayZ at 30-50 FPS all maxed out, still on old QX9650. Recording with dxtory still impacts 5fps, but doesnt matter, these are great chips, what you need is a better GPU.
After lots of research for budget setups, I would recommend GTX 650 TI BOOST, GTX 660 or GTX 760 (your CPU will bottleneck last two), 670 is not worth it atm money/performance wise. Or 7850, 7870 from AMD. All these cards will be able to max out DayZ with AA (5) and stuff.
However second problem is your clock. It is very low for Arma 2. I upped my QX9650 to 3.66Ghz and i got extra 10fps, but it was running hot and unstable, so i had to back down. Your chip is amazing in a sense that it offers good and smooth gameplay, but 2.4Ghz is just not enough for that game. Any current 100 euro CPU will easily give you performance required. My wild guess is that 8320 would easily yield 80% performance, and that's huge, since at 4Ghz it's easily 60% upgrade to QX9650.
I am not sure if this helps in any way, but feel free to check out my dayz playlist on youtube at /raymix1 ... it shows the enormous difference gained by upgrading the GPU alone.
My GF has Q6600 atm with 650 ti BOOST and she is playing WoW, Tomb raider and Deadpool maxed out at smooth 60 fps.
Hope my info helps you somehow.