Introduction

Four months ago, ATI officially announced their first multi-GPU solution called CrossFire.

Two months ago, we previewed and benchmarked it.

And today, ATI lifted their NDA on CrossFire performance with the Radeon X850 XT.

Contrary to what we were all led to believe, CrossFire cards are still not available, so today, we have little more than what we had two months ago when we previewed the platform.

Obviously, drivers have improved tremendously since we first benchmarked CrossFire, but as you will soon see, the platform still isn't entirely perfect. You will also find that CrossFire performance is decent, however plagued by an unfortunate GPU limitation limiting current CrossFire setups to a 1600 x 1200 maximum resolution.

The timing of today's NDA lift is curious at best, given that ATI's next-generation GPUs are literally just around the corner. In fact, given things such as the current 1600 x 1200 resolution, we honestly wonder why this performance introduction wasn't delayed until ATI's R520 launch.

Meanwhile, NVIDIA has steadily been improving the quality and availability of their SLI platform, which was announced over a year ago. Across the vast majority of their product lines, ATI is playing a seemingly never-ending game of catch-up. From the delayed release of the R520 to CrossFire, things haven't been looking up for ATI. Let's see if the trend continues here today.

The Details of the Resolution Limit
POST A COMMENT

76 Comments

View All Comments

  • DerekWilson - Tuesday, September 27, 2005 - link

    Actually, we took our time. Copied a few numbers down incorrectly. Sorry about that. Reply
  • Googer - Monday, September 26, 2005 - link

    Why hasn't anyone tested these on an nForec 4 motherboard yet? ATL Crossfire on a DFI SLI motherboard, will it work? Reply
  • OvErHeAtInG - Monday, September 26, 2005 - link

    Um, no. In the future, with different drivers? Who knows. But nvidia is unlikely to provide good nF4 drivers for people who are buying ATI cards? Reply
  • Live - Monday, September 26, 2005 - link

    How is the total power draw calculated, before or after the PSU? Reply
  • DerekWilson - Monday, September 26, 2005 - link

    Sorry I didn't explain -- I'll add the info

    power draw is measured before the PSU -- so yes, the dissipated power of the supply itself is included. And I do know that power draw at the wall is not exactly linear with respect to power supplied to the computer. At the same time, watts pulled from the wall are what we pay for right? :-)
    Reply
  • Dangher - Monday, September 26, 2005 - link

    You do realise that without proper homework you are just perpetuating sensationalism, right? The TMDS receiver has nothing to do with actual framerate or screen refresh, you do know that, right? You are aware that 1600x1200@60Hz in the TMDS translates into about 2500x1500@100Hz when doing SLI (or Crossfire, as is the case), right? Now go do your homework and correct the article (you're liable to be sued for libel by ATI btw). Reply
  • overclockingoodness - Monday, September 26, 2005 - link

    LOL, you are such an idiot. AnandTech can't be sued for libel; did you ever take business 101? Apparently not. Please keep your mouth shut on the things you have no clue about. Reply
  • DerekWilson - Monday, September 26, 2005 - link

    sorry m8, don't know where you got your info, but regaurdless of the fact that it is possible for the output to be run at a higher resolution than the TMDS receiver doesn't matter when the product manager of CrossFire at ATI states that the output of CrossFire will be locked to 1600x1200@60Hz *because* of the single link TMDS receiver.

    I'm sorry if I didn't make it completely clear that ATI could decouple their output from the reciever but they have chosen not to.
    Reply
  • Pete - Monday, September 26, 2005 - link

    The TDMS receiver is specced to the TDMS transmitter on the slave card, so it is indirectly tied to the screen refresh. I don't recall Derek saying it limits the frame rate, but obviously you can't see more frames than screen updates, so it can potentially limit the visible framerate, too. Yes, that applies to anything with a different frame than refresh rate, but XFire is fairly limited at 16x12@60Hz.

    And, no, you don't double up TDMS rates with XF, as the CE (Compositing Engine) doesn't have a buffer to accomodate a refresh rate independent of TDMS rate (which is, again, limited to 16x12@60Hz).
    Reply
  • Dangher - Monday, September 26, 2005 - link

    It is late and I can't be bothered to look for the techie article on this particular problem and why it's been blown out of proportion, but I will do it tomorrow and post a link here. My apologies to Derek if I offended him, it really is late. Link upcoming. Reply

Log in

Don't have an account? Sign up now