Radeon HD 4870 X2: Four Cards Compared

Radeon HD 4870 X2 And HD 4870 X2 CrossFire (4CF) Compared

In the following tables we will show you where the 5% performance increase comes from with two dual-chip cards with HD 4870 X2 (CrossFire 4CF) over one dual-chip card.

The single-chip Radeon HD 4870, two of which can be combined via CrossFire, is labeled with the CF abbreviation. The dual-chip card carries an X2 in its name, which points toward the internal CrossFire link of two graphics processors. When combining an X2 dual-chip card with a single-chip card, you will get 3CF, CrossFire acceleration with three graphics chips. When combining two X2 dual-chip cards via CrossFire, you’ll have four graphics chips running concurrently, which is then labeled as 4CF.

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CombinationsGraphics Chips
Radeon HD 48701
Radeon HD 4870 CF2
Radeon HD 4870 X22
HD 4870 + HD 4870 X2 3CF3
HD 4870 X2 + HD 4870 X2 4CF4

With Assassin’s Creed, the test cards are limited by the CPU—we can only guess how far the values could possibly go up with more processing horsepower. The little hiccup of 4.8% is not an error in the measurement, as we repeated the test several times. When the CPU is limiting frame rates, the results are not surprising. Essentially, the combination that uses the CPU least wins. Four graphics chips don’t give any advantage by overclocking the CPU, since even two graphics chips don’t have enough processing muscle to show off their best numbers.

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Assassins Creed in fps12800xAA16800xAA19200xAA12804xAA16804xAA19204xAAOverall
HD 4870 X2 4CF 8.10 QX@3.6765.770.165.651.450.051.9354.7
HD 4870 X2 8.10 QX@3.6765.466.967.551.352.252.8356.1
Performance difference in percent0.54.8-2.80.2-4.2-1.7-0.4

At 1920x1200 with anti-aliasing (AA) the advantage is no less the 40%. The 4CF combo will need higher resolutions to see even larger differences.

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Call of Duty 4 in fps12800xAA16800xAA19200xAA12804xAA16804xAA19204xAAOverall
HD 4870 X2 4CF 8.10 QX@3.67249.5250.6252.7248.1243.7249.41494.0
HD 4870 X2 8.10 QX@3.67276.2265.4226.5239.3199.9177.11384.4
Performance difference in percent-9.7-5.611.63.721.940.87.9

Crysis and the overclocked test CPU are at their limits, so the additional graphics chips of the 4CF combo just draw down extra system power.

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Crysis High in fps12800xAA16800xAA19200xAA12804xAA16804xAA19204xAAOverall
HD 4870 X2 4CF 8.10 QX@3.6733.
HD 4870 X2 8.10 QX@3.6734.
Performance difference in percent-2.9-2.9-3.2-2.5-1.7-3.1-2.7

Even at very high quality you don’t see a difference. Either the CPU power is not sufficient, or AMD’s drivers are horribly unoptimized in this one. We have heard suggestions from AMD that changes made to 8.11 improve performance, but in our experience with the beta driver, Crysis numbers didn’t budge at all.

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Crysis Very High in fps12800xAA16800xAA19200xAA12804xAA16804xAA19204xAAOverall
HD 4870 X2 4CF 8.10 QX@3.6728.325.425.126.823.822.5151.9
HD 4870 X2 8.10 QX@3.6729.426.325.727.424.423.8157.0
Performance difference in percent-3.7-3.4-2.3-2.2-2.5-5.5-3.2

The result in Quake Wars was expected because similar results of single- and dual-chip cards have shown that one graphics chip is enough to play the game smoothly.

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ET: Quake Wars in fps12800xAA16800xAA19200xAA12804xAA16804xAA19204xAAOverall
HD 4870 X2 4CF 8.10 QX@3.6786.483.883.283.182.682.7501.8
HD 4870 X2 8.10 QX@3.6790.187.689.186.486.386.1525.6
Performance difference in percent-4.1-4.3-6.6-3.8-4.3-3.9-4.5

This is also the case in Half Life 2. One graphics chip is enough for this game, more than that would be a waste with these test settings.

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Half Life 2 Episode 2 in fps12800xAA16800xAA19200xAA12804xAA16804xAA19204xAAOverall
HD 4870 X2 4CF 8.10 QX@3.67128.4119.8120.1125.9121.1120.7736.0
HD 4870 X2 8.10 QX@3.67130.3123.5119.9128.6123.4122.4748.1
Performance difference in percent-1.5-3.00.2-2.1-1.9-1.4-1.6

Using Mass Effect it is easy to test whether several graphics chips are working at all. The upgrade from the single-chip card HD 4870 to the X2 result in a performance gain of 80% and the 4CF combo gave us another 76% on top of that. The developers of the UT3 engine know what they’re doing. Scaling with the number of graphics chips is simply gigantic. Although the CPU power has some influence, four graphics chips still run nicely when other 3D engines have already given up.

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Mass Effect in fps12800xAA16800xAA19200xAA12804xAA16804xAA19204xAA12808xAA16808xAA19208xAAOverall
HD 4870 X2 4CF 8.10 QX@3.67129.8126.8124.3126.0123.0120.5125.4123.7121.51121.0
HD 4870 X2 8.10 QX@3.67131.2129.7125.0116.287.670.6114.185.769.0929.1
Performance difference in percent-1.1-2.2-0.68.440.470.79.944.376.120.7

Interesting here, but expected. No win, no loss, the additional graphics chips simply get ignored.

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MS FlightX SP2 in fps12800xAA16800xAA19200xAA12804xAA16804xAA19204xAAOverall
HD 4870 X2 4CF 8.10 QX@3.6729.529.729.529.829.829.7178.0
HD 4870 X2 8.10 QX@3.6729.129.729.429.829.829.3177.1
Performance difference in percent1.

When looking at the constant results at different resolutions, you will see the CPU limitations for both cards. When two graphics chips don’t get enough data, four won’t do the job any better. Only with a stronger CPU will you get more performance.

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World in Conflict in fps12800xAA16800xAA19200xAA12804xAA16804xAA19204xAAOverall
HD 4870 X2 4CF 8.10 QX@3.6752.753.652.651.451.952.3314.5
HD 4870 X2 8.10 QX@3.6753.556.154.550.052.952.5319.5
Performance difference in percent-1.5-4.5-3.52.8-1.9-0.4-1.6

When just looking at games with the UT3 engine, 4CF pays off at high resolutions, but on the whole, it is clear that available CPUs are too weak to support four fast graphics chips well enough to justify the extra cost, heat, and power. The gain in performance will increase with the next hardware generation. Until then, the fastest graphics chips will always perform similarly to the pair of chips you get on a single X2 board. Maybe it is even possible to run 16x anti-aliasing with the 4CF combo, but it’s up to you to decide if this really pays off in high resolutions.

  • Not only do we have four super-fast Radeon HD 4870 X2s to test, but also a list of 31 other graphics configurations including CrossFire and SLI setups. If you're in the market for AMD's fastest card available, you'll want to see this.

    Radeon HD 4870 X2: Four Cards Compared : Read more
  • neiroatopelcc
    "Because of accessories and price, Sapphire is our best-buy recommendation."
    One slight warning about sapphire though. If you have problems, don't expect their support team to help you before you've solved the problem yourself!

    I made a ticket regarding some issues with my 4870 on august 7th, and received a reply on the 26th of september! That's 46 days to address an error they simply stated would go away with a bios upgrade from their homepage!

    As for the article, I actually liked the detailed driver errors they encountered. Not that I liked the errors themselves, but I liked them being explained. Usually you just read 'after spending some hours resolving driver errors ....' without getting any wiser.
  • Pei-chen
    Wow, AMD cards consume power like a Detroit SUV. I like Nvidia GTX 2xx series’ Toyota Prius like efficiency at idle.
  • ilovebarny
    Why didnt they use the GTX260 Core 216? its like way better than the regular GTX260. And i just read yesterday that Nvidia was only going to make GTX260 Core 216 now. http://www.fudzilla.com/index.php?option=com_content&task=view&id=10497&Itemid=1
  • ilovebarny
    And i wish they had SLI'ed the 9800GTX+.
  • Chizops
    Why didn't they try using core i7 (extreme maybe)
  • enforcer22
    Pei-chenWow, AMD cards consume power like a Detroit SUV. I like Nvidia GTX 2xx series’ Toyota Prius like efficiency at idle.

    Hmm your right. Power house vs crippled mouse.. yeah your analagy sucked im sure mine did to but all i saw from what you typed was i like weak stuff dont give me more power.
  • bdollar
    seems to me if you are going to be comparing the highest end cards and even crossfire them for 4x you would have the highest resolution as one of the options. i would think people considering going x2 in crossfire would consider a 30" screen.

    don't get me wrong, i liked the article but would have liked to have seen the resolution spectrum hit the top.
  • It's nice to see the 9800GX2 included in the tests. I was considering the 4870x2 due to all the rave reviews but they never had the comparison like this against my current 9800GX2. I won't be getting new card anytime soon it seems. Thanks.
  • cleeve
    Wow, tons of info there, Tino. Nicely done!