CPU or Graphics Card Upgrade?


Jan 5, 2013
Short story, I mainly play the horror survival game DayZ and am currently playing on an i3 3220 and HD 6850 on a 1680x1050 monitor. Getting about 40-50fps in forest and drops to around 20-30 in cities. Playable, but I've got some extra cash to upgrade. Ive only got around $300 and so am not too sure which component would be bottlenecking my system. Ive heard different things about how dayz uses more cpu than gpu etc. If it were any other game I'd upgrade the 6850 to a gtx 660 ti and leave the cpu but Im unsure what the deal is with dayz.
Any advice would be great

Thanks :)