Half-Life 2: Episode One
The Source game engine uses an integer data format for its high dynamic range rendering, which allows all of the cards here to combine HDR rendering with 4X antialiasing.

Both GeForce 8800 cards can run Half-Life 2: Episode One just fine without the assistance of a second GPU. The GTS averages over 60 frames per second with HDR lighting, 4X AA, and 16X aniso. SLI does scale up from there, but I'm not sure Alyx at 100Hz is any better than Alyx at 60Hz.