I play all the recent games at maximum settings with my good old Radeon HD4870. It is balanced with the
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And if you don't believe me, I can assure you I'm totally serious. Getting recent and highest tier GPU never was a good idea and still isn't now. Most of the time that is where you will find the worst value for money. Getting recent low tier is worse mind you, because you won't be able to do anything with it. Just buy the most popular high tier chipset of the preceding generation and you are guaranteed to get almost the same performances at a fraction of the price.
Crossfire/SLI settings are utterly useless, except if you really need that half dozen of HD screens. But if you have the screens you probably won't have any trouble buying the cards.
As a rule of thumb, when you have performance problems in games you should always be sure it's not a CPU bottleneck first before buying anything. Because in more than 80% of the time, it is a CPU problem (and I know what I'm talking about).