will this run arma 3 with ok fps

Should be OK for medium details, maybe some high. The GPU is the weak link.

Using BF4 for comparison, most people are pairing the FX 6300 with good cooling, a mild OC to the 4.4-4.5GHz range, and an R9 270 or 280 class GPU. That is a well balanced midrange gaming system that won't break the bank.

Another alternative is something like the FX 6350 + Gigabyte 970A-UD3P OC system in my sig. It will be a little more but will support something like an R9 290 or GTX 970 fairly well.
 
A10-6800K is APU, this is not what You want. FX-6300 is 30-40% stronger as CPU. So no.

Just go for GTX 660 Ti, or 760 Ti, or R9 270/270X.

If You want APU for gaming, You "must" go for A10-7800 Pro or something, or at least 6790K. But it's a hazzard. APUs are strong for gaming, but not as strong as dedicated VGA, like GTX 660 Ti/GTX 760 Ti.
 
APU can run games, but it doesn't "play them well" :\. If You know what I mean. If You want to play so badly, ask guys to create You computer for games, up to 500 dollars. I personally wouldn't go APU way, never ever. CPU You picked is solid, FX-6300, even better would be some 760K or so. And I'd go "at least" for GTX 750 Ti. It'll do much much much more good than APU.