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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  • rjm55 - Friday, July 22, 2005 - link

    It seems silly to moan that you can't test higher than 1600x1200. Reality is 19" flat panels are reasonable and a hot buy right now - and they do 1280x1024. To get higher res you have to go at leasr 20" at TWICE the price for 1600x1200 maximum res. Except for the wide scren res blips of 1920 x1200 in the 24" category, the next big jump is at a 30" LCD with the Apple Cinema 30 doing 2560x1600.

    The point is 1600x1200 or the slightly higher 1920x1200 wide screen is the realistic limit for current LCD displays. It might be nice to know 7800 SLI works more efficiently at 2560x1600 but this is mostly academic since most readers here don't have a 30" Apple Cinema (we all know Anand does).

    For me I was very impressed that the ATI chipset and ATI Crossfire more than held their own compared to nVidia even in this preview setup. I'm looking forward to Crossfire chipset tests and overclocking tests to see if this is my next AMD chipset for a nVidia 7800. The nF4 stills seems way too flakey to me and everything I read says the new ATI chipsets run and overclock like a dream. Bring on some chipset results.



    Reply
  • jkostans - Friday, July 22, 2005 - link

    This reminds me of when ATI released the 9700 pro, except they are taking the beating this time. They will recover, these companies always seem to. I think the R520 is going to suprise many people, they are keeping awful quite about it. Also, rememebr that ati is an expert at staying alive with sub-par high-end cards (radeon 8500 and before). The low-end cards are what keeps these companies alive anyways, look at how many pre-built systems have an X300 in them..... Reply
  • Jalf - Friday, July 22, 2005 - link

    Why didn't the article look at how much of a relative improvement X-Fire gives compared to SLI?

    Yes, Crossfire beats the 6800 SLI in HL2, but what does that mean? A single X850 card beats a single 6800 in that game too.
    But 6800 SLI gives a 22% improvement over single-card SLI, while X850 Crossfire only gives roughly half that. (in the no-AA HL2 test. Too lazy to work out all the figures)

    Isn't that where it gets interesting? It's no big surprise that two fast cards beats two slightly slower cards, but knowing which multi-card technology provides the biggest boost over single-card speeds, would be a lot more relevant.
    Reply
  • Myrandex - Friday, July 22, 2005 - link

    It is pretty sweet that ATI has nvidia SLI working, and dual 3D1 support. Quad GF6600's sound pretty sweet (or Quad 7800's w/ Asus's solution).
    Jason
    Reply
  • smn198 - Friday, July 22, 2005 - link

    Xfire does give a good % increase over a single card which is promising for ATI's next generation assuming that it will be competitive with the 7800 series. Shame that the current performance doesn't look that good compared to 7800 SLI. Reply
  • gibhunter - Friday, July 22, 2005 - link

    SLI is a waste of money when you can buy a 7800GTX for $550 at newegg. The increase in power requirements, setup headaches, AA headaches is simply not worth it when you get basically the same kind of performance from a single card.

    Still, it's good that they have implemented the technology, then again it's completely asynine to require a special, more expensive card to have it running. SLI is cheaper.

    Finally, it's stupid to buy this setup just so you can run at 2048/1536 with 4X AA. No one with that kind of cash, runs on an old crt. Everyone with that kind of money has an LCD that's either 1280/1024 or 1600/1200 and for those, a single setup based on the 7800GTX is the cheaper and more reliable solution...unless you're an ATI fanboy. If so, then go waste your cash.
    Reply
  • shabby - Friday, July 22, 2005 - link

    Looks good, but when will it hit retail... when pigs fly? Reply
  • GhandiInstinct - Friday, July 22, 2005 - link

    ATi is worrying me a bit.

    They're losing customers everyday to the 7800, shouldn't they tease us who haven't converted just a bit so we know they're still alive out there?

    Send us a teaser spec or something please!
    Reply
  • Johnmcl7 - Friday, July 22, 2005 - link

    It's a real shame ATi didn't launch their X8xx series crossfire six months ago as #3 says, just seems a waste of time now, roll on R520.

    John
    Reply
  • PeteRoy - Friday, July 22, 2005 - link

    Crossfire will not be what ATI profits from, it needs more value fast cards like Nvidia 6600GT and 6200 Reply

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