NVIDIA GeForce GTX275 SLI Review - HL2: Episode 2

Using Half-Life 2 as a benchmark has had its share of ups and downs. In our first benchmarks we used the Lost Coast stress test under WinXP (in 32-bit mode, with great success). In the mode to Vista x64, we found that the game would not load properly (defaulting to 64-bit mode). Considering the extremely high scores that even low-end cards post, we decided to shift Source benchmarking to Half-Life 2: Episode 2, using the benchmark from HOC Bench.

The Episode 2 benchmark proved fine early on. It was more stressful that the Lost Coast tool, and provided a measure closure to current Source Engine load. However, we first noticed problems when we began to benchmark the GTX 275 in SLI. Performance we don't significantly over a single GTX 275. Googling the issue found general performance problems in 64-bit mode for Half-Life 2. I remembered that the Episode 2 benchmark ran slower in Vista versus XP, but I had originally attributed that to the overall performance hit for Vista - not an issue unique to 64-bit mode.

So, the first thing we will look at is the comparison of the 64-bit performance, versus the 32-bit performance. Looking at the first chart, we can do an easy analysis. The pairs of bars (blue-green, yellow-orange, red-purple) are the 64-bit and 32-bit performance of each card. The first bar in each pair is the 64-bit benchmark.

As you can see, only rarely does 64-bit provide any benefit - single GTX 275 1792MB at 2560x1600 and 1920x1200. In many cases the 64-bit executable provides a noticeable detriment. This is particularly noticeable in the GTX 275 1792 MB SLI setup. The 64-bit version of Half-Life 2 produces about 20fps worse performance.

Considering this finding, we migrated to the 32-bit executable and added back the Lost Coast benchmark. I no longer had the GTX 275 896MB card, so we don't have tests with in and the 32-bit version. However, based on the existing data from the last benchmark (which used the 64-bit version) we can extrapolate that the two GTX 275 cards would be comparable.

The GTX 295 continues to be the clear winner, hitting 100fps in Episode 2 and crossing 150fps in Lost Coast. In the Episode 2 test, the SLI setup provides a minimal improvement. The Lost Coast test shows a more noticeable improvement with the SLI setup.

However, the single GTX 275 is basically overkill - event at 5040x1050. The demos don't showcase any intense action sequences, so some areas in the actual game may slow down a bit. But, we can easily recommend a single GTX 275 for Source Engine games - all the way to 5040x1050 Surround Gaming.