So im sure if you've looked at the build a pc forum there was an already built computer for 350 that was built with a gigabyte MOBO, radeon r7 260x GFX, a8 6600k CPU, 128gb ssd, and 450W PSU. Will this run arma 3 and if so how well? I havent gotten it yet, but they put a stress test on it with aida64 and it was at 60 degrees C if that helps.
ARMA 3 is very, very CPU bound. So cpu bound that you will want to get an intel. I personally use a 8350 running at 4.8 GHZ and a 290x, I never get above like 25ish fps. If all you want to play is ARMA, get a pentium g238. If you want to play a lot of other games, get an i5. But games now are starting to require at least 4 cores.
Though with my 8350 at 4.5 GHZ and My GTX 770 I get 30 to 50 FPS with prolonged drops to 20 when any action occurs.
I wouldn't call it CPU bound. It's un-optimized and still coded in C++ maybe in some sort of single threaded format. That's why multiplayer is slower than single player too. They need to run it into a multi-threaded C++ code optimizer.