Super-AA and Video Performance
Due to the fact that ATI has incorporated their compositing engine onto the GPU die, we decided to run a handful of tests using the various Super-AA modes available when running a pair of X1950 Pro cards in a CrossFire configuration, and compare the results to those attained with NVIDIA's Quad-SLI. Please note, the compositing engine used on the X1950 Pro should offer higher-performance in Super-AA modes than the original engine used on the early Radeon Master cards. The X1950's compositing engine can do the final blend with each individual card running at full speed, which should result in higher performance.
Obviously, comparing ATI's mid-range offering to NVIDIA's current flagship isn't exactly an "apples to apples" scenario, but the data shows the benefit of ATI's compositing engine regardless. As the number of samples is increased, ATI's architecture takes less of a performance hit, and as such, the Radeon X1950 Pro CrossFire rig with 14X Super-AA is able to hang just behind a Quad-SLI rig when it's running in SLI16X mode. SLI32X AA performance is much lower than any of the ATI modes, but that's to be expected given the level of pixel processing being applied to the image. What also interesting to note is that the Super-AA modes that also incorporate 2X super-sampling (10x and 14x) out perform the other modes by a decent amount. It seems incorporating the compositing engine into the GPU die results in somewhat better performance because frame data is worked on by a single chip now.
For our next round of tests we took another look at Digital Video processing performance between the two competing core GPU architectures. "PureVideo" technology is at work here for NVIDIA and "AVIVO" drives the ATI X1950 Pro card.
To illustrate CPU utilization when playing back WMV HD content, we used the Performance Monitor built into Windows XP. Using the data provided by Windows Performance Monitor, we created a log file that sampled the percent of CPU utilization every second, while playing back the 1080p version of the "Coral Reef Adventure" video available for download on Microsoft's WMVHD site. The CPU utilization data was then imported into Excel to create the graph below. The graph shows the CPU utilization for a GeForce 7950 GX2 and a Radeon X1950 Pro using Windows Media Player 10, patched using the DXVA updates posted on Microsoft's web site (Updates Available Here).
Average CPU Utilization (Athlon 64 FX-60 @ 2.6GHz x 2)
|GeForce 7950 GX2||Radeon X1950 Pro|
The GeForce 7950 GX2 and Radeon X1950 Pro performed similarly during the HD video playback test. Technically, the GeForce used slightly fewer CPU resources, but the difference is negligible.