Sandy09 :
it meets..d system requirnments ....
http://www.game-debate.com/games/index.php?g_id=1855&game=ArmA+III&p_make=Intel&p_deriv=Pentium+Dual+Core+E5300+2.6GHz&gc_make=ATI&gc_deriv=Radeon+HD+6670+Asus+Edition&ram=4&checkSubmit=#systemRequirements
A Pentium E5300 is already way too weak by modern standards, as well as the mobo. A 6670 should run ARMA decently, not great, but DDR2 RAM isn't cutting it. Most developers just assume everyone has DDR3 RAM now because it's the standard.
Your PC is too low-spec'd and old to play ARMA 3 and most other modern games.