Well, I have an old, obsolete graphics card ATI HD6850 (Sapphire) and it can play BF4 even with max settings :)
I'd say you can go with HD7xxx or HD8xxx cards (if you're into ATI that is, because I am) for better games ahead. :)
FYI, this one's got 1GB GDDR5 Memory, double-slot size, 128-bit. :)