ATI HD 2900XT CrossFire: Intel 975X versus Intel P35

Gaming Performance

As usual, gaming performance was tested with a variety of current games. We ran benchmarks with our standard 1280x1024 resolution with 4x antialiasing and with 8x anisotropic filtering (if the game has support) enabled. Given the number of users that run 19" LCDs these days, 1280x1024 represents one of the most commonly used resolutions. We decided to also stress the graphics subsystem since we are benchmark testing the core logic chipset to compare the performance of ATI CrossFire on the P35 and 975X platforms.

In order to do this we were particularly interested in increasing the resolutions and graphic settings of the graphics cards so we are including 1600x1200 4xAA/8xAF and 1920x1200 4xAA/8XAF resolutions. We feel these resolutions will be the best indicator of performance for users with a high-end CrossFire and CPU setup. Our review is based on the capability of the Intel P35 chipset and how well R600 CrossFire works on the ASUS P5K-Deluxe with the current 8.37.4.3 drivers. We will examine other GPU solutions with this chipset in our P35 article.

Battlefield 2

This benchmark is performed using DICE's built-in demo playback functionality with additional capture capabilities designed in house. When using the built-in demo playback features of BF2, frames rendered during the loading screen are counted in the benchmark. In order to get a real idea of performance, we use the instantaneous frame time and frames per second data generated from our benchmark run. We discard the data collected during the loading screen and calculate a result that represents actual game play. While DICE maintains that results over 100fps aren't always reliable, our methods have allowed us to get useful data from high performing systems.

During the benchmark, the camera switches between players and vehicles in order to capture the most action possible. There is a significant amount of smoke, explosions, and vehicle usage as this a very GPU intensive Battlefield 2 benchmark. We run Battlefield 2 using the highest quality graphics settings available in the video settings. The game itself is best experienced with average in-game frame rates of 40 and up.


The P35 CrossFire solution performs well at 1280x1024 but as we crank up the resolution our scores start to drop and end up being about 5% worse at the 1920x1200 resolution. We still found the P35 setup to be perfectly playable and did not witness any stutters or graphic anomalies during testing. We noticed the same results in our initial XP testing and since the single card results are actually better than the 975X we believe this issue is a limitation of the x16/x4 design. However, we firmly believe that driver optimizations could regain a couple of percent based on P965 testing with an X1950 XTX setup.

Serious Sam 2

This benchmark is performed using Croteam's built-in demo capability in the Serious Sam II engine. We utilize the included Branchester Demo and capture the playback results using the Ctrl-~ function. The benchmark features a large number of combatants, explosions, and general mayhem. The benchmark is primarily GPU sensitive with the actual percentage of GPU/CPU/Audio activity being displayed during the benchmark run. We typically find this game is very playable at average in-game rates of 60 and above. We maximize all settings except antialiasing and anisotropic filtering within the general and advanced video settings.


We see our P35 CrossFire setup performing 5% better at 1280x1024 and then following the same pattern in BF2 with it trailing the 975X platform by 10% at 1920x1200 as the game becomes GPU limited. As in the Battlefield 2 testing the game playback was perfect and generated all of the correct visuals. Considering the single card scores favor the P35 setup we once again believe the differences at the higher resolutions are due to a combination of driver maturity and the x16/x4 limitation in high data traffic games. The initial XP testing reveals the same pattern although the difference at 1920x1200 is 5% which leads us to Vista driver improvements still being required for CrossFire operation on the P35.

F.E.A.R.

F.E.A.R. uses a built-in performance test that generates graphical test scenes based upon the actual game engine. This test consists of a couple of different action sequences, a stressful water flyby, and heavy use of shadows while traveling through hallways. F.E.A.R. is a very graphics intensive game and we switch all settings to maximum for both the system and GPU. During our testing of F.E.A.R., we noted that the "soft shadows" don't really look soft and the performance hit is drastic, so we disable this setting. An average frame rate for F.E.A.R. can dip drastically during game play and that is not good for a first person shooter but the game is still playable around 35fps although we prefer a solid 45fps.


This game is still a GPU crusher when the settings are dialed up and our P35 CrossFire setup falls flat on its face in this game when compared to the 975X. The single GPU scores are indicating another issue with both driver optimizations and throughput issues on the DMI link. The minimum and maximum frame rates followed the same pattern and will be presented in the P35 chipset article. Our initial testing on the P965 platform revealed a minor difference in frame rates between the P965 and 975X chipsets so we think driver optimizations can close the gap in this game.

Quake 4

Our benchmark utilizes the IdNetDemo with the playnettimedemo option. This includes mainly outdoor areas with numerous players trying to kill each other. We tested the game with Ultra Quality settings (uncompressed normal maps), and we enabled all the advanced graphics options except for VSync. Id does a pretty good job of keeping frame rates consistent so in-game frame rates above 30 are acceptable for single player and 60 for multiplayer. The important thing to remember is this test will directly translate to an actual Quake 4 experience.


After seeing a consistent pattern in our other game tests we now see a complete flip in the CrossFire results. We see the P35 setup being around 8% faster on average across the CrossFire results although it loses in the single card results. We ran this test several times with different settings but the results were always the same. We attribute the differences to driver optimizations and game code for the most part as the single card scores are better than the CrossFire scores.

During actual game play the perception was the CrossFire setups were more fluid and "seemed" faster than the single card setups although the net timedemos said otherwise. We also ran our custom timedemo and the scores were just the opposite with the 975X scoring up to 12% better. However, this was one of our benchmarks that had issues consistently finishing under Vista and showed signs of rendering corruption during playback. At present, we would have to say that our Q4 test is almost completely CPU limited, and this is often not the case during actual gaming. We are working on a new benchmark at this time.