Catalyst 6.11 - Caught in the CrossFire - Test Setup and Crossfire Testing

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Catalyst 6.11 - Caught in the CrossFire
Test Setup and Crossfire Testing

Test Setup & Info:

Our test system includes mismatched cards as we previously mentioned.  Below is a list of the hardware and settings used for the article.

  • MSI 975X Platinum v.2 PowerUp Edition.
  • Intel Core 2 Quad QX6700 @ 3.2GHz
  • Crucial X1900XTX 512MB
  • ATI X1900GT 256MB
  • eVGA 7950GX2 1GB
  • 2GB Kit of Crucial PC2-8000
  • Seagate 7200.10 250GB HDD
  • Windows XP Pro SP2
  • Catalyst 6.11 Drivers
  • nForce 91.37 Drivers

Crossfire Setup
Crossfire Setup

As you can see above, we've got quite a mismatched setup, but according to the latest release notes this is supported by the Catalyst 6.11 drivers.  Both of these cards are "CrossFire Compatible" but are not CrossFire Master Cards.  Although the MSI 975X Platinum board is CrossFire ready, the actual Dual GPU rendering is accomplished purely by drivers over the PCIe bus.

Enabling CrossFire on this setup is very easy.  We jumped into the Catalyst Control Center, and selected the CrossFire section and simply clicked "Enable".  We received a message stating that because of the mismatched cards a reboot would be required.  I'm assuming this is to disable 12 of the Pixel Shader Engines on the X1900XTX.  After a quick reboot we were ready to rock.

Control Center & Device Manager
Control Center & Device Manager


For this basic look at Software Crossfire with the Catalyst 6.11 Drivers, we have only ran 3DMark benchmarks.  We ran 3DMark 2003, 2005 and the latest - 2006 and compared the results with a reference 7950GX2 graphics card.  Please keep in mind that the ATi CrossFire setup is limiting the X1900XTX to 36 Pixel Engines and therefore becomes a slightly overclocked X1900GT Crossfire setup.  According to ATi's FAQ, the X1900XTX will keep the same clock speed, but loses 25% of its Pixel Shader Engines.

3DMark Benchmarks


I absolutely applaud ATi for their recent CrossFire enhancements.  A couple of months ago I was talking with a few other hardware analysts and we all agreed that CrossFire was a dead horse.  With the release of the X1950Pro and the X1650 series that include integrated CrossFire support, my hopes actually picked up somewhat.  Now with the release of the 6.11 Drivers and the ability to take a couple of regular X1900 or X1950 series cards and build a Dual GPU setup, I'm rethinking my dead horse statement.

Back in July of 2005, (yes, it's been that long) nVidia released their 77.76 drivers that allowed for "bridgeless SLI" with a couple of SLI capable cards.  I give kudos to ATi for finally catching the idea over a year later with their Catalyst 6.11 drivers and software CrossFire.  What ATi adds to the pot is the ability to link together a couple of different models, instead of two matching cards that are required for SLI.  I'm sure that an established hardware CrossFire link will give better performance that by pure software and the PCIe bus, but it's a start and a welcome addition to those of you stuck with a couple of non-Master CrossFire capable cards.  Bridgeless SLI suffers the same performance loss without the SLI bridge, but it offers much better performance that a single card as we demonstrated with our DIY SLI with DFI: Free Performance? Article back in September of last year.

Performance with Software CrossFire on non-matching cards is nothing to get too excited about as they are both required to run with the same number of pipes.  In the future we hope to get a couple of X1650 or X1950 Pro cards and explore CrossFire in greater detail as it looks like it may finally be a viable alternative to those wanting more GPU power than a single GPU can offer.

ATi is heading in the right direction and we look forward to better Dual GPU support from them in the future.  Now if the only had DX10 hardware and OpenGL support for Vista . . .