ATI's Answer to SLI: CrossFire (The Motherboard)

As with NVIDIA's multi-card graphics solution launch, ATI is bringing to market their Radeon Xpress 200 CrossFire-Edition chipset. Motherboards based around CrossFire will feature 2 physical PCI Express x16 slots with x8 electrical connections. If the motherboard manufacturer implements it, the second PCI Express slot does not require a selector card and can be used with any other x8 or lower device. When only one graphics card is installed, the BIOS is capable of reconfiguring dynamically the number of lanes that the PCI Express slots run, provided that the motherboard includes support for this feature. Some vendors will sell motherboards set up just like NVIDIA's solutions (more on that later).



Limiting the cards to only 2 x8 PCI Express connections may be a bottleneck if a game makes heavy use of the bus. Of course, we will run into similar issues with NVIDIA's solutions when paired with games that are PCI Express intensive. Unfortunately, as none yet exist, testing of this category of application is very difficult.

The Xpress 200 CrossFire-Edition is also capable of supporting integrated graphics. One excellent feature of the Xpress 200 CrossFire system is that, on boards where the OEM has included integrated graphics and two display outputs, 6 displays can be driven simultaneously (two from the integrated graphics, two from the standard Radeon, and two from the CrossFire card). Having the ability to support so many displays, while also offering the speed up of multiple GPUs is quite compelling; especially if ATI allows multiple GPU operation alongside multiple display support.

The need to buy a new motherboard in order to upgrade to a multiple GPU solution will likely keep some people from upgrading, but NVIDIA's solutions have the same problem. The fact that CrossFire is only being offered for the X800 and X850 series does limit the upgrade potential at this point. We have been recommending against using multi GPU solutions as an upgrade path option, but offering that freedom is still a plus.

ATI has given us the indication that CrossFire should work on Intel Chipsets as well as their own. This could give new life to those Intel designs originally targeted at SLI. Though not explicitly stating that CrossFire will work in an NVIDIA SLI board, it definitely seems possible. From an adoption/compatibility standpoint, ATI is certainly "evaluating other options".

There is also no physical reason why SLI cards could not work in an ATI Xpress CrossFire-Edition motherboard. The only thing that should stand in the way of this combination is NVIDIA's driver support. With the price premium that NVIDIA charges for their SLI chipset, it is clear that they want to discourage users from going another route. As they had owned the market on multi GPU solutions until now, that was an option. Now that ATI is throwing some competition in the ring, it would not be smart to exclude potential customers from using SLI just because of their motherboard choice.

Index ATI’s Answer to SLI: CrossFire (The Card)
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  • yacoub - Tuesday, May 31, 2005 - link

    Is it just me or do several things about this scream "bottleneck" and "latency"? The 2PCI-E x8 slots instead of x16 slots. The extra Compositing Engine chip. The ability to pair different cards such that it will drop clock speeds and/or pipelines to sync them up. The lack of direct chip-to-chip interconnect.

    I'm curious to know just how much performance gain is realized if you pair, say, an X800XL and an X850-something, over just the X850-something. And also how much bottleneck and latency there is in this implementation over the NVidia offering of SLI.

    The only upside I can see is cost/upgrade since a user can own an X800-based card (assuming they have a Crossfire compatible motherboard) and go out and buy an X850-based card later and use BOTH cards together (assuming they are both Crossfire-capable cards). Then again with those assumptions I'm not sure it's truly any more cost-effective. =\
    Reply
  • LoneWolf15 - Tuesday, May 31, 2005 - link

    As usual, the fanboys of both sides come to the show to spout their comments.

    For everyone saying "Man, you have to buy a Crossfire that matches your card, and throw it away when you upgrade"...umm, don't you have to buy two of the exact same matching card for running nVidia SLI, and if you wish to upgrade, you have to sell both? Doesn't sound that different to me. One thing I think a lot of current ATI owners will be happy about is that they won't have to get rid of a card they already own and buy two of a new one; they can just buy a single Crossfire card (and of course a mainboard).

    On the other hand, to those thinking ATI has now "0wned" nVidia, it is WAY too early to tell. The solution looks promising, but if you have to sacrifice mainboard performance (i.e., SATA hard disks, memory bandwidth, etc.) it may be a hard sell. Benchmarks in Doom 3 are also not the end-all be-all. We'll have to wait for a more comprehensive performance review, including DirectX benches, and performance/quality with older games using this new AA method, as well as game compatibility reports. We'll also need to know what TRUE pricing is (we've seen claimed pricing vary quite a bit from what it has turned out to be at product release in the past two years).

    Do I hope it will beat nVidia's solution? You bet. I like ATI, but even more I like competition that drives the industry. Do we proclaim ATI the winner/loser on this one? Heck no, it isn't even a purchaseable product yet.
    Reply
  • ElMoIsEviL - Tuesday, May 31, 2005 - link

    23 - They ran Doom3.

    It's not an ATi game at all as we all know. And it still does REALLY well. And it's not in release stages yet.

    ;)
    Reply
  • ElMoIsEviL - Tuesday, May 31, 2005 - link

    hehehehe.. it's better then SLi... hehehehe

    Figures, all the NV on here prolly aren't too happy today.

    I can't wait to test out the new AA modes.. :)
    Reply
  • vertigo1 - Tuesday, May 31, 2005 - link

    This is insane, who on earth will buy this?! Reply
  • JarredWalton - Tuesday, May 31, 2005 - link

    30 - Yes. The PCIe bus likely provides slower performance, as it is used for lots of other things (like communication between the CPU, RAM, and GPUs). I believe NVIDIA SLI works without the dongle but at slower speeds - at least, I heard that somewhere, but I haven't ever had an SLI board so I can't say for sure. Anyway, since DVI is a digital signle, using DVI in/out seems about as good as the SLI bridge - at least in theory. Now we just need to wait and see how theories pan out. :) Reply
  • Jalf - Tuesday, May 31, 2005 - link

    I was under the impression they were going to use the PCI-E bus for transferring data between the cards. Is the external dongle going to handle that instead? Reply
  • Murst - Tuesday, May 31, 2005 - link

    I really don't see how the xfire is better than sli based on hardware compatibility. Sure, you don't need the exact same cards, but you will likely buy only one x850 type card per x850 xfire. It would be extremely unlikely that someone upgrades from x850 xt pro -> x850 xt pe.

    Basically, in the end, you will buy a specific xfire tailored to your gfx card, and throw it away with the next generation of cards.
    Reply
  • gxsaurav - Tuesday, May 31, 2005 - link

    Great this just means more heat, man, even a single 6800 nU playes everygame fine, while running cool Reply
  • ViRGE - Tuesday, May 31, 2005 - link

    #21, yes it is. This is what hurts ATI the most, Nvidia already had 4 release cycles of experience with motherboards(2 of those being highly popular, highly recommended boards) before attempting SLI. ATI has a previous launch for a board almost universally ignored. I would not use an ATI board at this time, so I would also not consider CrossFire. ATI needs to get CrossFire working on Nvidia's boards to have a fighting chance this round. Reply

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