What Does DirectCompute Really Mean For Gamers?

Benchmark Results: Battlefield 3 At 1920x1080

We tested Battlefield 3 by using Fraps and recording a 90-second section of the Going Hunting mission. On page four, you may have noticed our inclusion of a screen space ambient occlusion (SSAO) screen capture. SSAO is a pixel shader-based approach to ambient occlusion originally developed for the game Crysis.

In a nutshell, the SSAO pixel shader samples every pixel’s depth value and works to determine the amount of occlusion from each sampled point. Because this is very resource-intensive at high resolutions, SSAO frequently employs random sampling coupled with post-processing blurring. As you can see in the earlier screen grabs, DirectCompute-based AO yields more realistic results...but at what cost?

True to DICE’s word, the answer is “not much.” Even though BF3 isn’t playable at 1920x1080 on our APU configuration, and severely bottlenecked when we drop a Radeon HD 7970 into the same platform, there is only a minor difference in frame rate response switching between HBAO and SSAO. Even turning AO off gains only about 5%.

In terms of total frames generated, we see the same story from another angle.

We should point out that, apart from an obvious message about the need for discrete graphics with this caliber of game and resolution, note the 2.2x performance difference between the FX and A8 platforms hosting the same Radeon HD 7970. This speaks to our continued emphasis on building balanced platforms. Clearly, although Battlefield 3's campaign mode is regarded as graphically challenging, your choice of CPU should reflect the caliber of GPU you use. Both need to be considered in tandem.

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