I bought a pc and didn't think about the graphics card before hand... Now I want to play BF4 at Medium if possible at high or ultra graphic settings, the graphics card im running right now is a Nvidia GT 610(Shit).
The R9 270 and 270X are the same card. The 270 is just clocked at a slower speed. You can usually overclock a 270 to 270X or faster speeds meaning the 270X, which is more money, is pointless.
The R9 280 has more stream processors and is a bit quicker than a 270 but of course costs more.
While the 270 or 7870 will do the job at 1080p the 280 will make for a smoother, better experience. Right now the prices are cheap and worth getting the 280 instead.