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Crossfire/SLI

By hewybo
Jan 24, 2006
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  1. Still trying to learn about graphics and gaming; came across this from PC World.


    January 24th, 2006

    GeekTech: ATI's CrossFire, Take 2

    Sr. Editor Tom Mainelli

    Graphics giant ATI hasn't done a whole lot right lately. From product
    delays, to product launches on paper only, to just plain disappointing
    performance from some of its newer products, the company has not
    enjoyed much critical success of late. But I have to give the ATI
    folks credit--they keep trying.

    Case in point: the company's CrossFire technology. Back in October,
    ATI launched its long-delayed dual-graphics card product, a response
    to NVidia's well-established dual-card SLI technology:
    http://www.pcworld.com/news/article/0,aid,118782,tk,urx,00.asp

    CrossFire was clearly a "me too" product, and the first iteration felt
    more like a proof of concept than a real-life product; I recommended
    that buyers steer clear:
    http://www.pcworld.com/news/article/0,aid,122980,tk,urx,00.asp

    Now the company has finally rolled out its next generation of
    CrossFire boards. They're clearly a step in the right direction,
    addressing some flaws and upping performance. ATI is trying to get it
    right.

    But I still wouldn't buy one.

    Better Performance, Still Kludgy

    CrossFire requires a special chip set and motherboard to work; ATI
    recommends dual-slot motherboards based on its own Radeon XPress 200
    chip set, which are finally beginning to appear in retail. Unlike SLI,
    which lets you pair most matching mid- to high-range cards, CrossFire
    requires one special-edition graphics board that includes extra
    hardware (the master) and one standard card (the slave). You connect
    the two using an awkward external cable.

    We performed our initial CrossFire tests using a Radeon X850 CrossFire
    Edition and a Radeon X850 XT board. The results were disappointing.
    For starters, the dual-card configuration was hamstrung by a
    resolution limitation of 1600 by 1200 at a refresh rate of 60 Hz (the
    new CrossFire cards face no such limitation). Worse, even paired up,
    the aging X850 chips had a hard time keeping pace with a single card
    running NVidia's 7800 GTX with 256MB of RAM; I shudder to think how
    badly NVidia's newer, faster 7800 GTX cards with 512MB of memory would
    thrash the dual X850 setup.

    This time around, we started by subjecting the same X850 boards to our
    latest graphics tests. Then we tested the next-generation Radeon X1800
    XT CrossFire Edition with 512MB of RAM paired with a standard X1800 XT
    512MB board. Finally, for comparison purposes, we tested the single
    X1800 XT board. Because CrossFire requires a compatible chip set, we
    can't test it in our standard graphics test bed machines (the ones we
    used for our recent graphics-board extravaganza). As a result, we
    can't really compare those results to those of our CrossFire test
    machine, so we have a rather limited data set.

    That said, we do know one thing: The new CrossFire is better than the
    old CrossFire.

    Test Results

    In our tests using Battlefield 2, Half Life 2, and Quake 4, the dual
    X1800 XT setup was a consistent winner over the dual X850 setup. At a
    lower resolution (1024 by 768), and with antialiasing turned off, the
    differences were laughably small on many of the tests. That's due in
    part to the fact that the CPU becomes more of a bottleneck than the
    graphics chip at those settings. However, at 1600 by 1200 with
    antialiasing turned on--a setting you'd expect from anyone spending
    the dough for two high-end graphics cards--the performance jump was
    more noticeable.

    For example, in Battlefield 2 at those settings, the dual-card X850
    setup notched 54 frames per second, the single X1800 XT hit 70 fps,
    and the dual-card X1800XT reached 80 fps.

    In our Half Life 2 test at 1600 by 1200 with antialiasing on, the dual
    X850 setup actually outpaced the single X1800 XT card with scores of
    105 fps to 88 fps respectively. The dual-card X1800XT hit 113 fps.

    Finally, in our Quake 4 tests at those same settings, the dual-card
    X850 setup managed 57 fps, the single X1800XT hit 54 fps, and the
    dual-card X1800XT reached 96 fps.

    Clearly, the latest generation of ATI cards are a step forward, and as
    a result pairing two such cards together nets better results than
    putting together two older-generation cards.

    SLI Remains Superior

    So why can't I recommend the new and improved CrossFire? For starters,
    the whole external cable connector thing still really bugs me, as it's
    nowhere near as elegant as SLI's implementation. And I don't like the
    fact that you have to pay more for the CrossFire Master Edition card
    than for the standard version. Finally, unless you're a die-hard ATI
    fan with lots of money, the results just don't warrant the cost. Of
    course, you can probably make the same argument about high-end NVidia
    cards and SLI:
    http://www.pcworld.com/reviews/article/0,aid,123791,pg,5,tk,urx,00.asp

    This latest CrossFire discussion may be moot. At this writing I'm able
    to find the standard $500 X1800 XT boards online, but I have yet to
    find the CrossFire version. If the cards don't show up soon, they may
    become as irrelevant as those first X850 CrossFire cards: Rumor has it
    ATI is already close to launching the 1800XT's replacement.

    Perhaps ATI's third attempt at CrossFire will be the charm.
    :)
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