Multi-GPU Scaling: Two 3850s = One 8800 GTX?

AMD only sent us a pair of Radeon HD 3850s for this review (believe it or not, we had to beg to get a single 3870), so our only CrossFire numbers come from this setup. That being said, the performance is quite respectable:

Believe it or not, but a pair of these $179 Radeon HD 3850s actually gives you the same performance as a single GeForce 8800 GTX.

 Multi-GPU Scaling (2560 x 1600) Radeon HD 3850 CF GeForce 8800 GT SLI
Oblivion 1.7x 1.87x
Unreal Tournament 3 1.48x 1.66x

 

Scaling looks pretty good from the Radeon HD 3850, however it's still not as good as what NVIDIA is able to achieve with the 8800 GT. NVIDIA consistently achieves about 11% better scaling from one to two GPUs than AMD.

The other problem with CrossFire is that it simply doesn't always work, so a pair of 3850s is not necessarily a better option than a single 8800 GT or GTX. Case in point would be the two other games that we wanted to include here: Quake Wars and Call of Duty 4, both gave us lower frame rates with CF enabled than without. AMD's release notes for the Radeon HD 3800 drivers informs us that some applications may show a performance decrease with CF enabled, so we're not too surprised.

While it'd be nice to be able to purchase two cheap cards and get better performance than the best out there, there are simply too many caveats to really embrace the idea.

Out with the Old, in with the Mid-Range Power Consumption
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  • Roy2001 - Thursday, November 15, 2007 - link

    Well, once I played games with AA enabled, I would never turn it off. I would rather lower the resolution.
  • falacy - Thursday, November 15, 2007 - link

    That's a giant "ME TOO!" for me.

    my old ATi 9800XT would run 4x AA at 1024x768 in most games and I found that more enjoyable than running 1280x1024 without AA. The 60Hz fliker of the monitor at 1280x1024 played a role in that I am sure, but mostly the trouble with gaming without AA is that objects in the distance tend to shimmer in an unnatural way that seems to pull me out of the moment. So, indeed lower resolution + 4x AA = a better experience than higher resolution that has distracting artifacts.
  • DrMrLordX - Thursday, November 15, 2007 - link

    Alright, thanks. I actually overlooked the AA tests on Oblivion. Silly me.

    Mostly I was interested in knowing if the 3870 had better results running with 4x AA than the 2900XT. Interestingly enough, the 3870 doesn't seem to lose a lot with 4x AA, especially at high resolutions. The 8800GT is another story.
  • munky - Thursday, November 15, 2007 - link

    But... I'd like to see more games benchmarked, and with AA preferably.
  • StormRider - Friday, November 16, 2007 - link

    Is anyone else bothered by the transistor count of 666 million? Couldn't they have done something so that it was 665 million or 667 million instead?
  • aeternitas - Tuesday, December 11, 2007 - link

    lol How stupid. As you go out using this card to obviously kill some sort of opponent, you're bothered by this?
  • Kaleid - Friday, November 23, 2007 - link

    Just a number, nothing more to it.

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