NVIDIA SLI-AA

NVIDIA introduced special SLI-AA Modes beginning with driver version 77.7x. By running Coolbits, selecting "Advanced Settings" under "View" in the "Performance & Quality Settings" area, and selecting "SLI-Antialiasing" under the "SLI Rendering Mode", you have new options to run games at 16xAA or 8xAA independent of application control. There are many potential advantages to SLI-AA mode. You can find more information on how this feature works and the potential benefits at NVIDIA Announces 16x AA For SLI.

Since some have reported dramatic increases of up to double the speed using SLI-AA with the Dual x16 board, we ran benchmarks in SLI-AA modes using the same Far Cry game using our Regulator benchmark. As in our other testing the CPU, memory and drivers were the same for both boards. We even moved the hard drive between the two test setups to make sure everything except the motherboard was exactly the same. Since we had some problems with stability of the release 81.85 drivers in SLI-AA mode, we used the more recent 81.87 drivers which are also available in the Beta section at nVidia's wesite.

nVidia SLI-AA Mode - 1600x1200 - FPS



As you clearly see from the test results we did not find ANY performance improvement in either SLI-AA mode on the Dual x16 board compared to the Dual x8. In fact, the DFI Dual x8 was slightly faster than the Asus Dual x16 in theses tests. The results, however, were well within error tolerance and are equivalent - no difference. Perhaps more memory or lower resolutions would yield different results, but in the past we have consisitently found higher resolutions to benefit most from SLI and antialiasing.

Gaming Performance Overclocking and Features Performance
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  • Per Hansson - Sunday, November 6, 2005 - link

    Hi, what type of capacitors did Asus choose to use on this mainboard?

    It looks like all caps are of the same type, (bar the CPU filter caps) is it Chemicon perhaps?
  • Klaasman - Sunday, November 6, 2005 - link

    You guys at Anandtech should try cleaning the dust out of your HSF once in a while.
  • Wesley Fink - Sunday, November 6, 2005 - link

    We have received a number of emails questioning our results since some other sites who found twice the performance with Dual x16 tested with the nVidia SLI-AA option enabled with Coolbits in very recent nVidia drivers.

    We have complete results of SLI-AA testing with Far Cry - Regulator, the same game tested by sites claiming the 50% performance gain for Dual x16, but we no increase at all in SLI-AA performance.

    ALL components except the motherboard are the same. We even moved the hard drive between the systems to make SURE everything but the motherboard remained the same. Results were the Average of two runs with the very latest 81.87 videodrivers. Memory was 2x512MB of our standard OCZ PC3200 Platinum Rev. 2 at 2-2-2-7. Memory and CPU were exactly the same in both systems, and the same MSI 7800GTX cards were used for benchmarking.


    nVidia SLI-AA Mode - Far Cry - Regulator Demo - 1600x1200

    8X SLI-AA 16X SLI-AA

    Asus A8N32-SLI Deluxe 37.22 20.59

    DFI LANParty nF4 37.89 22.19

    As you clearly see, there is NO difference with nVidia SLI-AA between Dual x8 and Dual x16. In fact the Dual x8 scores are slightly faster, but they are well within error margin and I would call them equivalent - the same.

  • Live - Sunday, November 6, 2005 - link

    Nice to see this one cleard up. To bad you where right and they where wrong, performance wise that is.
  • mctmcpoop - Saturday, November 5, 2005 - link

    Cound you re-test and compare the result from different X16 bus in A8N32 ? If the X16 slot result from the NF4 chipset is lower compare to X16 from C51D , we can be sure that the C51D X16 is much faster than NF4 chipset
  • Wesley Fink - Saturday, November 5, 2005 - link

    This is a really good idea. The only problem is the Micro ATX boards that have this North Bridge do not normally have the memory timing options and other tweaks to allow a direct comparison. Also with an enabled integrated video on the C51 north bridge we are introducing a new variable. We will probably have to wait for other Dual x16 boards to see if we can duplicate these results on the newest, most demanding games.
  • mctmcpoop - Saturday, November 5, 2005 - link

    What I mean is test both of the X16 slot on A8N32 , one X16 bus should be from C51D pci express tunnel chip , the other X16 slot bus should be from the NF4 chip as other normal SLI board ... So if the right X16 slot get good score compare to left X16 slot , that means C51D chip has better design of the pci express x16 bus ...
  • Wesley Fink - Sunday, November 6, 2005 - link

    I ran some quick tests comparing the North x16 slot (nearest to CPU) and the South x16 slot on the Asus in the 3 new games that showed the big single-video increases. The South x16 slot was consistently slower than the one nearest the CPU by 2% to 6.7% in our single video performance tests. Perhaps there are difference in performance of the MCP51 and nF4 SLI which each drive one of these slots. We will look at these results again in future Dual x16 board reviews.
  • lopri - Saturday, November 5, 2005 - link

    Another question for Wesley:

    When you say OC isn't as good with SLI as with a single video card setup, is it in general? Or this particular board? Also, what's the reason for it? CPU? Chipset? Power regulation on the board?

    Thanks again for a great review! I'm eagerly waiting for this board!
  • Wesley Fink - Saturday, November 5, 2005 - link

    We have noticed that SLI will not overclock as high on other nForce4 boards as well, but I can't tell you the max on each one for SLI. I made this comment because I couldn't duplicate an overclock I had run earlier on this board, realized I had SLI set-up, removed the 2nd card and ran a few quick tests to see the impact of SLI on maximum overclock.

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