All of the benchmarks were performed at stock speeds of 325/600 and what I found
to be a very stable overclock of 440/875.
Also, all benchmarks were performed
with a single NX6800-TD128E as well as two of them in an SLI configuration.
You can use this percentage calculator to play around with the various
differences between any combination of single, SLI, default, or overclocked
Half-Life 2 is CPU limited as well but it really depends on the area of the
game. As you can see below, the at_c17_12 and at_coast areas
basically flatline at 1024x768 while 3dnews_canal shows some substantial
gains even at that low resolution.
Here is an example of the command line I used for the tests below: