Introduction

This week, we were very lucky to get our hands on a CrossFire motherboard and a CrossFire master card from Gigabyte.

We have previously covered CrossFire, so please check out that article for more details. It all comes down to ATI's answer to SLI in the form of a master/slave card combination where the master card reconstructs the data produced by both cards and outputs it to the display. Communication between cards is done over PCI Express and a dongle that plugs into the slave card's DVI port. And today, we have the pleasure of talking about performance.

While we did get the chance to take an early look at CrossFire during Computex, we recently learned that what we saw wasn't actually full CrossFire. This time, we have an actual master card in our hands and we'll put ATI's answer to SLI to the test. Of course, due to the very prerelease nature of these products, our tests were not without some bumps and detours.

We had some trouble getting CrossFire set up and running due to a combination of factors. The first monitor that we tested doesn't work on the master card dongle with drivers installed. We weren't exactly sure in which slot the master card needed to be (we hear that it shouldn't make a difference when the final product is released), and we didn't know into which DVI port on the slave card to plug the dongle. After a bout of musical monitors, slots, and ports that finally resulted in a functional setup, we still needed to spend some time actually wrestling the driver into submission.

After getting the driver issues squared away, we got down to testing. Our first disappointment came along when we realized that the CrossFire AA modes were not quite finished. Enabling these modes drops performance much more than what we would expect and looks like the frames that each GPU renders are out of sync with the other card. We can't be totally sure what's going on here, but it's clear that there still needs to be some work done.

One thing that works well right now is SuperTiling. Except for some random display corruption when switching modes, SuperTiling looked alright and ran with good speed.


Note that each GPU will render 32x32 pixel blocks (256 adjacent quads for those keeping track).


The only random quirk that we would expect to find in prerelease hardware, which ended up getting in our way, is the fact that setting standard AA modes in the control center didn't seem to actually enable antialiasing. Games that made use of in game AA adjustments seemed to work well. Not being able to use a good CRT monitor, we had to resort to our 1600x1200 LCD for testing, limiting our max resolution. Below 16x12, many games are not GPU limited under CrossFire. Even at 16x12 with no AA, we see some games that could be pushed much further.

This brings up a point that we will be making more and more as GPUs continue to gain power. Large LCDs are very expensive and CRTs are on their way out. Buying more than one 6800 Ultra, and soon adding a CrossFire master to an X850, doesn't make much sense without being able to run more than 1280x1024. And we would really recommend being able to run at least 1600x1200 for these kinds of setups.

Let's take a closer look at the setup before we get to benchmarks.

The System
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  • BroadbandGamer - Friday, July 22, 2005 - link

    "#23, I think you may be the only person out there who uses an LCD for gaming without scaling the resolution up to native."

    I never scale a lower res. I'd rather play the game with black bars around it then look at a nasty scaled image. So the guy is not alone, there's lots of us who don't like scaling lower resolutions to fit the native resolution of the screen.
    Reply
  • DerekWilson - Friday, July 22, 2005 - link

    #39, You make a good point about people reading the article. But it is important to make it clear that spending more than $900 on graphics hardware may not be worth it unless the user wants to run 1600x1200 or higher.

    -----

    We've updated the article to include percent increase tables on the last page. CrossFire ends up being pretty competitive with SLI in terms of % increase.
    Reply
  • johnsonx - Friday, July 22, 2005 - link

    do we have any information yet that says an ATI Crossfire setup will or will not work in an NForce4-SLI board? Reply
  • saiku - Friday, July 22, 2005 - link


    Just so most people without bazillion dollars to spend on these systems get a clue, how about posting 6800 GT, 9800 Pro, 6600 GT numbers. Maybe then we could decide to sell the house and buy the XFire solutions.

    Why the moaning about not running above 1600x1200? What percentage of people reading this article will be running it above those settings , I wonder?
    Reply
  • bob661 - Monday, July 25, 2005 - link

    quote:

    What percentage of people reading this article will be running it above those settings , I wonder?


    There's probably quite a few people here running it above those resolutions. Remember, this is a geek site. :)
    Reply
  • blackarc - Friday, July 22, 2005 - link

    #37 - ROTFLMFAO!!!!!



    *sigh*

    I love my dual 19" LCDs
    Reply
  • yacoub - Friday, July 22, 2005 - link

    Wow, where to begin with this one...

    =====#23 no serious gamer would play in a window,====

    OH NOES IM NOT A SERIOUS GAMER NOW. :'(

    ====and how can you not see the drawback of shrinking the screen size to get a lower resolution?=====

    I'm not shrinking anything, I'm putting it at its natural size. And again, I only do it to run certain games smoothly on my aging system. I see no drawback to running a 1024x768 window'd game on my desktop for games like UT2k4. Sorry, I just prefer that. I also like to be able to Alt-Tab without all the drama (time wasted) reloading of the screen that happens when you run a game in full-screen mode anyway. I'm different that way I guess. OH NOES, DIFFERENCES R BAD!

    ======Why turn a 19" display into a 14" display?====

    Except I'm not? I have a 17" display and I'm using it all, I just put some games in a window on the desktop - you know, like you do with many other pieces of software that you don't want to take up your entire view, or in the case of some games that run better at a lower res on my system.

    =======I'm sorry but my 21" crt can do any resolution and still use all of the screen space and not interpolate.====
    And mine can do any resolution up to its maximum just fine as well and in a manner I am happy with that does not "interpolate" or distort. Thanks for playing. M

    y system's not spec'd enough to run 1280x1024 in the latest games. Since I'm GOING TO BE PLAYING IN 1024x NO MATTER WHAT, why not do it in the most efficient manner where I can also keep an eye on other tasks? And so that's what I do. :)

    ======LCDs can't period and that's a big deal for 99% of gamers.======
    Most gamers have machines that can run the native res of 17" or 19" LCDs. I don't anymore since some games are too much for my system. I was simply answering the faux complaint about, "OMG IT STRETCHES TEH GAMES IN NONNATIVE RES" because it certainly doesn't on mine nor on most modern LCDs that have more than simply "stretch image" as a way to display lower resolutions! *gasp* Imagine that! Technology changes and improves! Ignorance must be bliss though.
    Reply
  • ann111 - Friday, July 22, 2005 - link

    My desk just looks a hell of a lot nicer with a dell 2005fpw and hyundai l90d+, which together take up less space than my old sony 21" crt. Reply
  • DerekWilson - Friday, July 22, 2005 - link

    #23, I think you may be the only person out there who uses an LCD for gaming without scaling the resolution up to native.

    #28, we used an XT / XT combo for SLI, and the Far Cry benchmarks are not a typo. Nor are the XT PE labels. Sorry for the confusion, but it had been a while since I had run Far Cry numbers and the game favored CrossFire enough to make it worth a few quick tests on a couple other cards.

    #30, at this point no, we can't test on other chipsets. This product is still in developement and has a hard enough time getting enabled on all ATI hardware.

    Thanks,
    Derek Wilson
    Reply
  • Sunbird - Friday, July 22, 2005 - link

    #8, your wrong, CRT's are the win!

    The only reason I like LCD's is cause they have made big CRT's so cheap!!
    Reply

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