Graphics is infinitely parallel. There is always more work that can be done, and the work can be broken up into millions of completely independent operations. This is very different than most tasks we see done on the CPU that don't scale quite as easily with the number of cores. While we might see small improvements by adding another CPU, we can see nearly double the performance by doubling the number of processors in a graphics card (as long as there are no other bottlenecks anyway). This fact is why AMD and NVIDIA have invested so much money into their respective multiGPU solutions (CrossFire and SLI respectively).

MultiGPU solutions have been around for a few years now, and while we frequently include single card multiGPU solutions in our reviews, we only occasionally take an in depth look at multiGPU technology. Some time has passed since the last time we studied the issue, and now that we've fully broken in our Core i7 system, 64-bit Vista, and recent graphics drivers, it's time to get to it.

Over the past few weeks we've been benchmarking and analyzing lots of numbers. We've looked at single, two, three and four GPU systems across multiple games and resolutions. The configurations we chose to look at are current generation high-ish end hardware capable of operation in 3-way and 4-way configurations. Because of the sheer volume of data we collected, we've decided to break up our analysis into multiple articles.

This first article (the one you're reading right now) will cover single and dual GPU configurations (including single card multiGPU hardware). The next article will add 3-way solutions along with comparisons back to single and dual GPU setups. The final article will add in 4-way performance analysis and compare it back to the single, dual and 3-way data. Splitting up the analysis this way will allow us to dive deep into each type of configuration individually without spreading the content too thin. We can keep focus on a specific aspect of multiGPU performance and scaling while still making all the relevant comparisons.

The initial installment also introduces the Sapphire Radeon HD 4850 X2 2GB. Though we expected AMD to push the 4850 X2 out in the same way they launched the 4870 X2, we've only seen one version of the 4850 X2 hit the scenes late last year from Sapphire. In light of what we've seen, we are rather surprised that we haven't seen more fanfare behind this part from either AMD or other board makers. The lighter weight X2 competes more directly in price and performance to the GeForce GTX 280/285, and really fills out the lineup for AMD. Overall, the increased RAM in the 4850 X2 2GB enables great performance scaling even at resolutions the 512MB 4850 can't come close to handling.

As for the topics we'll cover, our interest will focus on scalability of the multiGPU solutions and the relative value of the same. Before jumping into the numbers, we'll cover the metrics we use to analyze our data. First, we'll look at scaling and talk about the big picture. Then we'll talk about what we've done to calculate a value comparison.

Who Scales: How Often?
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  • nubie - Sunday, March 01, 2009 - link

    Have you ever used a tool or edited the game profile yourself?

    I had an 8800GTS 320MB that I used with AA extensively (Also with 3D stereoscopic), and I was told on a forum to use nHancer to modify the profile into a specific mode of Anti-Aliasing, I am pretty sure it worked. It was the beta 162.50 Quadro drivers I believe, you can just put your card's id into the inf and they install and work great.

    It is possible the drivers work great and the control panel/GUI is piss-poor (a theory that may hold water).

    I wish that nVidia would open up the drivers a little so that control freaks like myself could really tweak the settings to where I want them.
    Reply
  • Razorbladehaze - Monday, February 23, 2009 - link

    Yeah In my main rig right now i have a i7 920 with two 1gb 4850's i recently bought a third 4850 and installed it. There was some funky flickering, that i think was driver related in BF2 and HoI2 in 3-way mode, but most games seemed okay. Funny thing is... same thing happened when i tried a 3870x2 & 3870 in 3 way on my older x38 core2. I am really hoping these next articles will come with some additional commentary on image quality.

    To the person who stated that the 9800gtx+ was comparable to the 4850x2. What R U thinking???

    I have never really had a problem with any crossfire setups before except with 3-way and i wonder if it is the odd gpu count and if 4 would eliminate some issues. Looking forward the the upcoming articles, this is mostly a teaser with information many already knew.

    I agree that the new format for graphs looks good line graphs are crap visually, but i think the default should be the 1920x1080/1200 that most people are interested in based on your survey data : )

    See I pay attention.

    Reply
  • SiliconDoc - Wednesday, March 18, 2009 - link

    THANK YOU !
    " Yeah In my main rig right now i have a i7 920 with two 1gb 4850's i recently bought a third 4850 and installed it. There was some funky flickering, that i think was driver related in BF2 and HoI2 in 3-way mode, but most games seemed okay. Funny thing is... same thing happened when i tried a 3870x2 & 3870 in 3 way on my older x38 core2. I am really hoping these next articles will come with some additional commentary on image quality. "
    ________

    Another PERFECT REASON to not mention "image quality" - the red fan boy wins again - assist +7 by Derek !
    Amazing.
    Thank you.
    Reply
  • MagicPants - Monday, February 23, 2009 - link

    Have you tried forcing on transparency super-sampling? If you don't edges defined by transparency in the texture won't AA. By default Nvidia (ATI?) only AA edges defined by depth difference. Reply
  • SiliconDoc - Wednesday, March 18, 2009 - link

    I've seen one review on that, with the blown up edged images, and the ati cards don't smooth and blurr as well - they have more jaggies - so they HAVE to leave that out here - cause you know Derek loves that red 4850 and all the red cards - Reply
  • Elfear - Monday, February 23, 2009 - link

    Derrick (or anyone else for that matter) can you comment on why the 4870 512MB Crossfire solution generally performed better than the 4870X2? Reply
  • SiliconDoc - Wednesday, March 18, 2009 - link

    Or WHY the GTX260 isn't praised to the stars for running 20 of 21 tests successfully - taking THE WIN !
    I guess it doesn;t matter when a gamer spends hundreds and hundreds on their dual gpu setup then it epic fails at games... gosh that wouldn't be irritating, would it ?
    Amazing red bias...chizo pointed out the sapphire 4850 / other 4850 driver issues thankfully, while Derek has a special place in his heart for the bluebacked red card, and says so in the article - then translates that to ALL 4850's.
    DREAM ON if you think that would happen with ANY GREEN card Derek has ever tested!
    Reply
  • MagicPants - Monday, February 23, 2009 - link

    I'd like to see an article that rates overall systems in price to performance. Try to get as high as fps for the least amount of money spent.

    As one reader mentioned frame rate below 15 fps doesn't count because it's unplayable, so just pick a number between 10 and 15 and subtract it from the fps. Maybe vary it by game. Frame rates over 60fps shouldn't count either because most monitors can't even show that.

    This would be interesting because even small tweaks would make a difference e.g. adding a $60 sound card might get you 4 or 5 fps in a few games and might pay for itself.
    Reply
  • marsbound2024 - Monday, February 23, 2009 - link

    It doesn't look like the GTX 260 Core 216 provides much, if any, tangible benefit over the GTX 260 according to these tests. Sure it had some wins, but they weren't very big ones and it also had some loses--albeit not very big ones either. One would be tempted to just get a GTX 260 or 4850 and wait to upgrade until the next generation of cards come out this summer. The time is getting close, anyways. Reply
  • SiliconDoc - Wednesday, March 18, 2009 - link

    Good call.
    Even the 4830 or the 9800GT twice either, or the 9800gtx gts250 or 9600gt or 9600gso twice each - or the ati the ati - uhh... uh... do the reds have their "midrange" filled up ? Uh.. the 4670 ?
    LOL
    Yeah, nvidia needs more midrange - right ?
    LOL
    THE RED LIARS ARE SOMETHING ELSE!
    Reply

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