Quad SLI part deux: Build It Yourself

Half-Life 2: Episode One

Publisher: Valve Software

Half-Life 2: Episode One is the first in a series of episodes that extends the Half-Life 2 story far beyond where the original left off. Valve has implemented its HDR rendering and used it to great effect in Half-Life 2: Episode One. There are also new higher-resolution textures, new facial animations and some AI improvements made in the new game too.

Anti-aliasing and anisotropic filtering were controlled from inside the game, and thus the drivers were left set to "Application Controlled". There are three options for the method of HDR used in this title. You can either disable HDR completely, make use of "Bloom" which is just what it says and less resource hungry in comparison to "Full" which, again is just what it says. It utilises a full dynamic range with the iris effect too.

We have written quite a bit about Half-Life 2: Lost Coast, Day of Defeat: Source, Episode One and how Valve have implemented HDR in to the Source Engine. You can check out the articles listed below for more information on The Lost Coast & Day of Defeat: Source.

• Half-Life 2: Lost Coast HDR overview
  
• Half-Life 2: Lost Coast hands on
  
• Half-Life 2: Lost Coast Benchmarks & Video
  
• Day of Defeat: Source
  
• Cinematic Effects in Source
  
• Liveblogging HL2: Episode One

We did a five minute manual run through from the Exit 17 level. It involves lots of HDR, lots of explosions and both indoor and outdoor scenes. The section we have used is typical of some of the more stressful areas in the game. Thankfully though, the game runs superbly on a wide range of hardware, while still looking absolutely stunning.

In Half-Life 2: Episode One, we encountered a rather strange and confusing problem - Quad SLI delivered virtually the same performance at 2560x1600 with 8xSLI AA, as it did with 4xAA. This may sound rather crazy, but it is because of the issues with DirectX 9, where it doesn't support enough back-buffers to queue enough frames up. NVIDIA knows about these issues, but it is likely that the issues will not disappear completely until DirectX 10 and supporting hardware turns up early next year.

At both 4xAA and 8xSLI AA with transparency supersampling enabled, we recorded frame rates of 40.0 and 39.8 fps respectively on the pair of XFX GeForce 7950 GX2 Extreme cards running in Quad SLI. The deficit for enabling transparency multisampling with 8xSLI AA was very small - only a single frame per second. Although the frame rate was low if you consider other platforms we've tested this game with, the experience was incredibly smooth - most importantly, the frame rate was very consistent.

Comparing performance of 8xSLI AA on the two platforms shows that Quad SLI was around 40% faster than a pair of BFG Tech GeForce 7900 GTX OC's running in SLI. This was the difference between a playable and an unplayable gaming experience.