CPU bottleneck. The 6100FX is not fast per core, since ARMA 2 loves its CPU single threaded speeds, that is your issue.
OC your CPU and you will see some improvement.
Ah, that presents another issue. This motherboard is completely dreadful for overclocking. I tried to overclock but when I did it just reduced my memory speed down to 800mhz. Thank you for the reply though