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Performance

AA and AF settings are applied in game, whenever possible. We had to apply AA and AF from the driver panel for Call of Duty and Richard Burns Rally. In Quake 4, we enable both AA and AF from the console, with the command 'r_multisamples' set to 4 and 'image_anisotropy' set to 16. V sync was disabled both from inside the game and on the driver panel. AA and AF is enabled from the settings menu for F.E.A.R, Serious Sam II and Splinter Cell: Chaos Theory.

Call of Duty and Richard Burns Rally was configured to the highest possible detail. F.E.A.R settings are set to our usual test settings (all settings set to maximum / on except for soft shadows). Quake 4 was set to 'High Quality' while Serious Sam II was tested with our usual standard settings (maximum settings but with custom resolution, anti aliasing and anisotropic filtering settings). The same also applies to Splinter Cell Chaos Theory - the game was benchmarked to use its shader model 3.0 and everything turned on, except for HDR which is only turned on for HDR performance tests.

We ran our usual tests under two different configurations - one with a single Radeon X1900XTX and another with a Radeon X1900 Crossfire Edition master card and the Radeon X1900XTX as a slave card. Catalyst AI was enabled so it will apply the best Crossfire mode (alternate frame rendering)

We'd like to thank ASUS for supplying the ASUS A8R32-MVP Deluxe motherboard, the Radeon X1900XTX and CrossFire Master card as well as Tagan for supplying the additional power supply for this article.

Our test setup
AMD Athlon 64 3500+ socket 939
2 x 1024 MB Kingston KVR 3-3-3 PC3200 DDR-SDRAM
ASUS A8R32-MVP Deluxe Radeon Xpress 3200 Crossfire motherboard
ASUS Radeon X1900 Crossfire Edition DDR3 512 MB graphics card
ASUS Radeon X1900XTX DDR3 512 MB graphics card
Maxtor DiamondMaxPlus9 80 GB Serial ATA 8 MB buffer
ASUS E-616 DVD-ROM
Tagan TG530-U15 530 watts ATX/BTX power supply

Windows XP Professional with Service Pack 2 installed
ATI Catalyst 6.5 reference driver
Realtek High Definition Audio 5.10.00.5202 driver.
DirectX 9.0c

Performance

The results:

The graphs are pretty self explanatory, but in case you can't see the text, they're arranged in groups of three colors: green for minimum fps, blue for average fps and red for maximum fps. The first group represent test results under default settings, and the second represent results with 4xAA and 16xAF enabled.  For Serious Sam II HDR tests, the second groups represent results with HDR, AA  and 16x AF. These results are in frame rates per second.


With such a high performing card like the Radeon X1900, we won't see dramatic increases like we did with two low end cards. Two Radeon X1900 in a Crossfire setup is not going to offer you higher frame rates than a single card in a system limited setup such as this. We only begin to see a difference at 1280 x 1024, where the single Radeon X1900XTX is trailing behind by 10 fps or so. That's not really significant with the results we're seeing here - about 5 percent slower. The trend continues at higher resolution, and here we see an even bigger gap between the two. It's interesting to note that with higher resolutions, even with Crossfire, we're getting slightly lower frame rates. So, maybe we're not that system limited after all.

Since Call of Duty is an outdated game, this is not unexpected. It's very likely we will see a similar trend with most, if not all, pre DirectX 9 games. In these games, having two Radeon X1900 in Crossfire mode allows you to have slightly higher frame rates in situation where the game is texture / pixel shader limited (usually by enabling AA / AF). From the results, we could see that the added pixel processing power of a second card will let offer less penalty when AA and AF are used in higher resolutions. For Call of Duty, instead of losing performance at about 15 - 25 percent, you're only losing 5 - 6 percent.

It's really not a great argument for going Crossfire. But of course, the extra processing power from the second card allows you to turn on graphical features that was prohibitively expensive with a single card, like adaptive anti aliasing. The next game we benchmark is particularly interesting for that reason alone. Let's take a look. 

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