Final Words

The final verdict on CrossFire is very mixed. It is clear from our Game tests that SLI has a worthy competitor with parts in its price range at 1600x1200@60Hz and below. However, we have a hard time buying the idea that many gamers are going to shell out the money necessary for CrossFire with that kind of limitation. With cards like the 7800 GTX out there, and more interesting hardware from ATI coming soon, we are very inclined to recommend a single card upgrade. That recommendation is especially true for users who have 1280x1024 LCD panels or want larger than 1600x1200 resolutions from their graphics card.

Fortunately, ATI has stated that near term future products will utilize dual-link TMDS receivers and allow users to run monitors like the 30" Apple Cinema display under CrossFire. While the TMDS communication is a very interesting solution to the multi GPU problem, limiting resolution based on available bandwidth just doesn't make sense to us. Scaling at the high end doesn't matter as much as compatibility. As long as bandwidth does limit output resolution, though, we are very happy to see ATI move to dual-link TMDS communication for their future parts.

It is very hard for us to support Super AA having seen the abysmal performance scaling we have shown here. With single cards using 4x and 6x AA more than doubling the performance of CrossFire with 8/10x and 12/14x AA, we can't understand why anyone would suffer the performance hit. In order for this to actually be useful, users would need to be monitor limited to 1280x1024 or below - in which case a CrossFire purchase is severely misplaced. At the high end, it is hard for us to believe that an increase in resolution to 1920x1440 (or even higher) would have as much of a performance hit. Maintaining a standard AA level on a high resolutions will likely provide better image quality than a low resolution with Super AA. It is also probable that performance would decrease less when scaling resolution beyond 1600x1200 than when enabling Super AA. Unfortunately, we don't even have the ability to test this theory properly with current hardware and drivers.

Despite exceptional performance at its target resolutions, we have to strongly recommend against the purchase of an X800/X850 series CrossFire card. (You also would probably need a motherboard upgrade for Crossfire anyway, making it even less attractive.) We have a hard time recommending all but the absolute top end NVIDIA 7800 GTX SLI as a viable solution. As an upgrade path, it makes generally much more sense to buy the next single card solution that comes out instead of spending money on older technology that won't scale as well, takes up a lot of space, eats up a lot of power, and likely incorporates fewer features. The only way we truly say that multi-GPU technology is a better solution than a similarly classed single card solution (even when upgrading from one card to two) is at the absolute highest end where there is no competition from a single card. And right now the king of the mountain is still a 7800 GTX SLI. But just how long will that last? Only time can tell.

Mode and Hardware Scaling
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  • davecason - Tuesday, September 27, 2005 - link

    http://www.anandtech.com/video/showdoc.aspx?i=2541...">http://www.anandtech.com/video/showdoc.aspx?i=2541...

    The word "us" should be "use" in this paragraph:

    The CrossFire master card is basically an X850 XT with the addition of a Xilinx FPGA (for the compositing engine) and a TMDS receiver for taking input from the slave card. Instead of 2 DVI-D ports, the CrossFire master card makes us of a high speed DMS port. This connects to one port of the CrossFire dongle and takes the slave card input as well as providing the output to the monitor.
  • JarredWalton - Tuesday, September 27, 2005 - link

    Fixed. I think that was a minor edit by me where I fixed one error and created another. Hahaha....
  • Wesley Fink - Monday, September 26, 2005 - link

    We will be posting an in-depth review of the ATI Crossfire AMD motherboard tomorrow. One thing no site has really talked about is what a great overclocker the ATI Crossfire AMD has become. The Reference Board has the best Enthusiast level options and controls I have EVER seen on a Reference Board, the overclocking performance is outstanding, and DFI promises they will deliver the same or better in the next few weeks in their own Crossfire AMD board.

    Another unmentioned biggie for me is the fact that the Crossfire X850 Master Card works just fine as a standalone X850 graphics card. If you have to buy a Master Card for Crossfire I think it's important to know you can use it ALONE as an X850 card when the next hot generation graphics comes along - it's not just an investment you have to throw away.

    Derek talks a bit about how the next generation graphics fixes some of his concerns about Crossfire as a TODAY purchase. His comments should make more sense in that light, and they will certainly be clearer in the next couple of weeks when X1800 launches. Just keep in mind that the same Crossfire AMD motherboard will be used with X1800 and that the motherboard also works great with an nVidia 7800GTX and any other single nVidia or ATI graphics card right now.
  • michal1980 - Tuesday, September 27, 2005 - link

    i have to say nice numbers by ati, but
    i mean who in the right mind is buying a 500 dollar x850 card, a 150-200 dollar mobo,
    just to get crossfire, when in 1 week or so the x520 is supposd to come out. which by the way does not appear to have any menition of crossfire support. and while true you do not have to buy the same 2 cards for crossfire to work. the 2nd master card you buy costs you 100 bucks more. phhff. sorry. the whole sli/crossfire thing really doesn't make much sense unless you are always buying at the release of the tech. i.e. when the gtx gets released u buy 2.

    but why would you buy into a crossfire setup now? when the next ati cards are coming out. if there similar to the nivida one. getting 2 x800s, is like roughly spending the money on 2 6600gts, when you could for the money buy the never, and overall better 1 card solution in a 7800gtx for the same money.

    or a new x520, for the same money, i'd pass on getting old tech up to speed when new stuff is/will be here soon
  • michal1980 - Tuesday, September 27, 2005 - link

    also if u do compare the 6800ultra vs the x850, the only game the ati car wins in is in hl2. go figure, a game they basicaly wrote for there hardware with the help of gabe 'i will delay this game till ati is ready'
  • DerekWilson - Tuesday, September 27, 2005 - link

    heh ... ATI was very unhappy with Valve's launch slip. They sank a lot of money into the HL2 bundle and launch efforts for a time frame that was a year before the game actually came along.
  • waldo - Monday, September 26, 2005 - link

    So, like most people on this forum, I read both here and at Tom's Hardware...and it is amazing to me the discrepancies in the writings of the articles. I was hoping you could clarify.

    1. Are they just bought out by ATI, or are you guys just bought out by NVIDIA?
    1a. The conclusions drawn seemed to be in the face of each other. You are dead set against, and they are seeming for ATI's crossfire. This isn't fashion, or poetry, or a film, where you just go by what you like. There are frame rates, quality of picture, etc....why are they so different?

    2. It appears that the benchmarks on Tom's are slightly different in comparison to yours, in that it shows the X850 crossfire doing slightly better than the 7800 SLI configuration in several instances.

    3. Tom's foxused more on the notion that you don't need two of the exact same card. Based on your article, it is your opinion that you go 7800 SLI, or single wiht hopes of 7800 SLI later, rather than x850 now, and then the addition of R520 later? It would be helpful to have some benchies of mixed card situations.

    I realize that it seems attacking, and really I posted here because I like Anandtech better than Tom's but I respect both as the best resources on the net for technology reviews, but it just seems odd that the two top sites out there come down on completely different sides of the fence.

    Thanks
  • Frallan - Tuesday, September 27, 2005 - link

    THG!

    Well as it seems THG has in the last two year gone from beeing a "not-so-good" hardwaresite (please buy it back Thomas) to currently beeing a "outright-bought" hardwaresite. Just look at the major articles they have published the last year and U will see.

    All IMHO oc.
  • photoguy99 - Tuesday, September 27, 2005 - link

    Tom's Hardware articles seem to be trending toward less interesting and less quality over time.

    I still read it, but most of the time find I prefer the AnandTech version of similar subjects.

    One thing that is terrible about Toms - why no direct link from articles to a discussion topic?

    Not only does it make it easier to discuss, but I consider it a huge benefit the the AnandTech authors read and participate in the discussion of the articles.
  • DerekWilson - Tuesday, September 27, 2005 - link

    Is this not a discussion? :-)

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