What can we say about Counter-Strike: Source that hasn't already been said before? It is quite simply the benchmark for team-based online shooters and, five years after its release, it's still one of the most popular games in its genre. It focuses on small environments and incredibly intensive small-scale battles with one-shot kills the order of the day. If you want to test all elements of your first person shooter skills in one go, this is the game to do it.
We test using the 64-bit version of the game using a custom timedemo taken during a game against bots on the cs_militia map. This has a large amount of foliage and is generally one of the most graphically intensive maps available. We find a frame rate of at least 60fps is required for serious gaming as this game relies massively on quick, accurate reactions that simply can't be compromised by dropped frames. All in-game settings are set to their maximum and we test with 0xAA 0xAF, 2xAA 4xAF, and 4xAA 8xAA.
As we're beginning to see more and more often, Counter-Strike: Source really doesn't pose a threat to graphics cards of this calibre. There's simply nothing to choose between the three cards on test.