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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  • yacoub - Friday, July 22, 2005 - link

    #17 - what native resolution "thing"? I quite often play at lower resolutions than my monitor's 1280x1024 and it windows it quite nicely on my over-two-year-old LCD (meaning the technology has been around for a while now to make it look good). It shows it at the actual resolution with black around it like a letterboxed movie on a TV screen. Or I simply play it in Windowed mode if the game supports that (most do) and that way I can keep an eye on my instant messenger messages while playing the game. :) Reply
  • yacoub - Friday, July 22, 2005 - link

    I'm glad to see Splinter Cell: Chaos Theory in the benchmarks because that game alone could justify someone's purchase of SLI/Crossfire cards. As can be seen in all the SC:CT benchmarks at Anandtech, it's quite the GPU-taxing game. Only with Crossfire or SLI'd 7800GTXs, are you looking at smooth gameplay of 60+fps in 1600x1200 4xAA (although since Anandtech doesn't post "Min" "Max" and "Average" fps numbers along with a graph of the fps throughout the testdemo, it's hard to know for sure that it never dips into slower territory. Reply
  • rjm55 - Friday, July 22, 2005 - link

    #15,16,17 - I just retired a 22" Diamondtron CRT earlier this summer. The REAL screen size was 20" and it did 2560x1600. This summer from hell made me realize how hot CRT's get. My computer room is at least 8 degrees cooler now.

    CRT's do fine in gaming, but they are declining. Most new sales are LCD. They may have to pry your CRT from your dead hands but LCDS are what people - and gamers - are buying. You don't have to like it, but it is still a fact.
    Reply
  • Frallan - Friday, July 22, 2005 - link

    #8

    [quote]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.[/quote]

    Nope Ure wrong re: price I got my 6800gt when it was new Ill soon be buyin a second 6800gt and I will have played the whole time and still sopent less.

    [quote]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. [/quote]

    BS - I have that kind of money and Im using my old CRT (EIZO F58) to goto 16*12@85Hz. So far have not seen 1 LCD that stood up to my standards re. color, responstime and resolution. So sorry Ure just plain wrong.
    Reply
  • Kegh - Friday, July 22, 2005 - link

    I will be replacing my current PC this winter with a new one. I do not see enough bang for your buck to go with xfire, especially since a single 7800gtx and presumability a single R520 will run within 5% of the xfire setup. Plus dealing with two cards = twice the heat / fan noise. Also xfire using 800 series gpu's is no bonus.

    I think this setup only makes sense if you currently own an 800/850 card. It "may" cost less to upgrade then. Wasn't the xfire 850 card going to retail for $550 (minus the $100 rebate which ati has going on) = $450... Plus $100+ for a new mainboard and we are back at $550... or you can buy a single 7800gtx for same amount and have an easy upgrade... Which would someone rather do?

    Most likely I'll go with a single R520. They should be out by xmas! :)

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

    #11
    "the performance increase from a single X850 XT to CrossFire is up 43% as opposed to SLI's benefit of 34% over a single card"
    I just can't wait till R520 comes out, then ATI and nVidia will have a real showdown.
    Reply
  • dmfcomputing - Friday, July 22, 2005 - link

    i always laugh at "gamers" with LCDs... the whole native resolution thing makes real gaming a pain in the ass. my 19" high end viewsonic CRT can do 2048 (but i only have a 6800gt, so not many games i can push up that high). I play almost all games at 1600, but if i got battlefield 2 (im not interested in EA crap like that tho) id have to switch to 1280, which would screw up your LCD. besides it costs a hell of a lot of money to get a 1600 LCD, much less a high res one. and honestly, the picture just doesnt look as deep as a good aperture grill CRT. and unless your paying tons of money for some 8ms LCD, youll get ghosting at good FPS levels. i will never buy an LCD as long as theres a good CRT out there. They just suck for gaming. Reply
  • Turin39789 - Friday, July 22, 2005 - link

    Agreed #15 - LCD's are nice, and getting nicer. But for gaming I don't feel you can beat a quality 21' crt. And with the way prices are falling ( I just got an off lease 21' for $100 + 50 shipping) you'll have even more money to drop on a nicer video card, or even a second monitor. Reply
  • MrSmurf - Friday, July 22, 2005 - link

    #13, most hardcore gamers who Crossfire is marketed to play on CRTs and should be able to hit resolution higher than 1600x1200. Reply
  • Warder45 - Friday, July 22, 2005 - link

    Nothing really that supriseing. Games where the X850XT beat the 6800 Ultra are the same games where X850XT crossfire beats the 6800 Ultra SLI, and vise versa. The 7800GTX is of course well as it's a next gen part; once the R520 comes out I'd assume to see some competition. I have to agree with those above, ATI really should have switched priorities and launched the R520 now and launched crossfire in aug/sept. Reply

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