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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  • MamiyaOtaru - Tuesday, February 24, 2009 - link

    So we have to be perfect in every way to point out errors? NBA players shouldn't listen to their coaches because their coaches can't play as well as they do? Game reviewers shouldn't trash a game because they couldn't make a better one? Reply
  • ggathagan - Tuesday, February 24, 2009 - link

    When it comes to grammatical errors as insignificant as the ones pointed out, yes.
    If you're going to be that critical, then you best check your own grammar.
    Reply
  • cptnjarhead - Wednesday, February 25, 2009 - link

    Grammar shmammar, you guys need to move out of your mom’s basement and get laid. :)
    Reply
  • bigboxes - Wednesday, February 25, 2009 - link

    +1 Reply
  • stym - Monday, February 23, 2009 - link

    I am curious to see how a pair of radeon 4830 would perform in this lineup. A single one is quite weak at those resolutions, but I am willing to bet a pair of those would hold its own against a single GTX280.
    Oh, and it would be much cheaper, too ($180 including the bridge).

    Could you possibly include that setup next?
    Reply
  • DerekWilson - Monday, February 23, 2009 - link

    You are right that a single 4830 won't be enough perform on par with these guys ... but I don't think two of them would really be worth it against the GTX 280 except maybe at lower resolutions. The 1GB 4830 will run you at least $145, so you're looking at $290 for two of them and the 4850 X2 2GB is the same price. The 512MB 4830 will be limited by memory usage at higher resolutions just like the 4850 512MB.

    We might look at the 4830 in CrossFire internally and see if it warrants an update, but so far it isn't in the roadmap for the rest of the series.
    Reply
  • stym - Monday, February 23, 2009 - link

    I was thinking 512MB 4830s, which are in the $90~$110 price range. That price range is the only reason I mention them, because it puts the price tag of a pair of those in the exact same range as a Radeon 4830 512MB or even a GTX260.

    You said that a 4850 1GB doesn't make sense, and that's even more obvious for a 4830.

    Reply
  • pmonti80 - Monday, February 23, 2009 - link

    I find too that this would be an interesting match at the $200+ pricetag. Reply
  • wilkinb - Monday, February 23, 2009 - link

    why not just drop AoC, it was bad when it came out, has always had issues and odd results and no one i know played for more then 2 months...

    If you want to have a mmo, why not use one that people play? and maybe even more mature in development...

    I know you will say it adds value, but you dont know its it bad code or showing a different view.
    Reply
  • ajoyner - Tuesday, February 24, 2009 - link

    Most of the issues with the game are gone. There are currently no other MMO's out there that have the graphics or combat system to tax a gpu like this game. Your comment on testing a game that people play is very subjective. There are many MMO's out there that I would not touch....WOW, cough, cough.....but that doesn't mean other people don't enjoy them. I think having this game as one that is regularly benchmarked adds a great deal of value to the article. Reply

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