I am planning on spending about 150-200 $ on a graphics card for my new computer. It runs at 1600x900 resolution (yah, not even 1080p). I was debating between a Radeon R9 270 and a 270x. Will the 270 be enough or should I go for the 270x? I wish to play games such as DotA 2 and Portal 2 (not BF4) on ultra settings at ~60 fps. I'm using an i5 4460.