Don't count on just the graphics card to fix all your gaming fps problems.
You'll want to look into your RAMs and your mother board.
Watt supply is also a factor.
Most cards can be overclocked so you should google up on how to do that.
If your computer is struggling with playing BL then it is most likely a cheap $400-$500 prebuilt machine from Dell or HP and slapping in the meatiest graphics card available isn't going to do jack stuff for you.
All the components in your system have to not only be compatible and in working order, but also up to comparable levels of performance. A great graphics card will be wasted on a computer without a decent CPU. In regards to "RAMs" (lol) and motherboards, the main thing to look for is compatibility and in the case of RAM, quantity.
It is true that a many graphics cards will scale back their performance if they are not receiving the juice they require to run and so having a quality, up-to-spec power supply is not only a matter of safety, it can effect your gaming too.
It is possible to overclock many components of a computer, but doing so is not as easy as clicking a button and comes with substantial risks. If you don't know what you are doing you may damage or destroy your computer, wasting hundreds of dollars in an instant. Also, the potential gains from overclocking will not be noticeable to the average computer user and the techniques are mainly used by those who get a kick out of seeing technology pushed to limit (the same kind of people who spend thousands of dollars on their computers).
If your computer is more than 1 or 2 years old and you really wish to upgrade, I would recommend building a whole new system, as jamming in a new graphics card isn't going to turn your aging pile of silicon into a raging, testosterone-filled beast of a gaming machine, despite what that "one website said".
