NVIDIA's SLI: Part 2 - 6800U & 6800GT

NFS: Underground 2

Publisher: Electronic Arts

The Need For Speed: Underground 2 is a game that we've spent a long time playing through recently, we've used it here to represent a typical driving simulator - it's based on the DirectX 9.0 API, and makes use of lots of DirectX 9.0 features, including motion blur and light trails. Anti-Aliasing was controlled from inside the game, while Anisotropic Filtering was controlled via the driver control panel, as the game does not feature in-game controls for Anisotropic Filtering.

We used a 3-lap race on the "Parkade Track 1" Street-X circuit with three opponents for our manual run through. The circuit is a fairly high-speed one, but contains lots of corners - it makes good use of motion blur and light trails.

In Need For Speed: Underground 2, we found that NVIDIA has chosen to adopt a custom Alternate Frame Rendering method for SLI, allowing us to scale performance when adding a second video card. We found the following in nvapps.xml:

   < PROFILE Label="Need for Speed Underground 2">

      < APPLICATION Label="speed2.exe"/>

         < PROPERTY Label="multichip_rendering_mode" Value="2430001" Itemtype="predefined"/>

   < /PROFILE>

The Point of View GeForce 6800 Ultra SLI was capable of running at 1280x1024 4xAA 16xAF with Maximum in-game details. We also found that the XFX GeForce 6800 GT SLI ran best at these settings too. We found the GeForce 6800 Ultra SLI was choppy at 1600x1200, even with 0xAA. We believe that the title is sufficiently CPU limited, and we had to lower details to allow us to attain a smooth frame rate at 1600x1200 with or without Anti-Aliasing.

When we used single card configurations, the Point of View GeForce 6800 Ultra was capable of delivering a smooth gaming experience at 1280x1024 2xAA 16xAF with Maximum in-game details. On the other hand, the XFX GeForce 6800 GT delivered a very smooth frame rate at 1024x768 with 4xAA 16xAF and Maximum in-game details.

Both the GeForce 6800 Ultra SLI and GeForce 6800 GT SLI combinations ran at the same in-game detail settings, with the only difference being an increase in frame rates. We saw an increase of a mere one frame per second on the all-important minimum frame rate, while the average frame rate increased by a under five frames per second. To be honest, we didn't notice any difference between two GeForce 6800 Ultra's and two GeForce 6800 GT's in this title, thus making the GeForce 6800 GT a more attractive purchase if you feel that Need For Speed: Underground 2 is an important title, taking up a large portion of your gaming fixation.