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Test Results: Synthetics

PCI Express & CrossFire: Scaling Explored
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It would be a huge mistake to skip over our synthetic results and jump straight to games, because our findings here can help to explain some of the unusual gaming results.

Our overclocked E8600 required FSB-1600 to reach 4.0 GHz, but most chipsets don’t support this bus speed natively. Overclocking the chipset itself means that the memory controller will operate at a higher performance level while consuming more power, producing more heat, and increasing the likelihood of data errors.

Sets of chipset parameters for a given bus speed are often called “bootstraps,” and correspond to the clock speed for each supported bus speed. Many motherboard manufacturers have been able to locate undocumented bootstraps in various chipsets, enabling these in an attempt to gain an overclocking advantage over the competition.

  • The 975X supports only 200 MHz and 266 MHz boot straps.
  • The P965 officially supports 200MHz and 266 MHz bootstraps, but our tests have indicated that certain boards may be accessing an unofficial 333 MHz strap.
  • The P35 Express officially supports 200 MHz, 266 MHz, and 333 MHz bootstraps, but our tests have indicated that certain boards may be accessing an unofficial 400 MHz strap.
  • The X38 doesn’t officially have a 400 MHz bootstrap, yet it’s there on most motherboards for everyone to use. That’s because its functionally identical to the FSB-1600 supporting X48 Express.
  • The P45 doesn’t officially have a 400 MHz bootstrap, but once again this unofficial setting is found in the BIOS of nearly every performance motherboard.

To rule out chipset overclocking as a cause for increased CPU performance, we first ran Sandra Arithmetic and Multimedia benchmarks.

With no discernible difference in CPU performance, it’s time to see what northbridge overclocking means in terms of memory performance. For that, we used Sandra’s memory bandwidth benchmark.

The farther a chipset was pushed beyond normal operating parameters, the more memory bandwidth the CPU had—almost certainly the result of overclocking the chipset’s memory controller.

But not every benchmark is affected by memory speed. For example, 3DMark Vantage tries to single-out the performance of the graphics processor and CPU. We expect PCI Express bandwidth to take on a far more significant role than memory bandwidth in these tests. For the following charts, we used the P35 Express to examine single graphics card performance in PCI Express 1.1 transfer mode, and the P45 Express to test a single graphics card in PCI Express 2.0 transfer mode.

As expected, 3DMark Vantage related its overall score almost directly to its GPU score, with CPU performance relatively constant.

But synthetic scores have little relevance to real-world performance, and now it’s time to see how each motherboard performed in actual games.

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  • 2 Hide
    badge , December 8, 2008 7:16 AM
    Thanks for laying that information out.
  • 5 Hide
    sparky2010 , December 8, 2008 7:31 AM
    should've included 1920x resolutions in the last page, as there are a lot of people out there with screens capable of that resolution.. but anyways, all in all a very good and informative article.. but i'm going to settle with a complete makeover when core i7 becomes more available!
  • -1 Hide
    V3NOM , December 8, 2008 7:32 AM
    yer kinda interesting to see how things have changed with new mobos but it doesnt really have any practical value tbh.
  • 5 Hide
    Crashman , December 8, 2008 7:38 AM
    V3NOMyer kinda interesting to see how things have changed with new mobos but it doesnt really have any practical value tbh.


    It's all about answering the question "Will a second card do the job".

    Lots of guys have midrange or better ATI graphics cards, and the question of "upgrade or replace" is constantly being asked.
  • 0 Hide
    outlw6669 , December 8, 2008 7:50 AM
    Thanks for finally getting this review out!
  • 1 Hide
    arkadi , December 8, 2008 8:07 AM
    p45 looks grate, and the price is right.
  • -9 Hide
    arkadi , December 8, 2008 8:08 AM
    btw x58 is out there, just a reminder.
  • 1 Hide
    outlw6669 , December 8, 2008 8:20 AM
    @ arkadi
    Yes the x58 is out.
    However, as it can not be paired with a Core 2 CPU and runs DDR3 exclusively, you can not directly compare the results.
    In general, I would assume crossfire on the x58 will scale similarly to the x38/48 as they both have the same PCIe configuration.
  • 2 Hide
    Crashman , December 8, 2008 8:21 AM
    outlw6669Thanks for finally getting this review out!


    It was planned for September but kept getting delayed due to tight deadlines on other articles. But when the economy finally went from a slow decline to a nosedive in November, we knew this article had to come out right away. More people are putting new systems on hold and looking for ways to keep their old ones up to current performance standards, and we care about upgraders just as much as system builders.
  • -1 Hide
    arkadi , December 8, 2008 8:41 AM
    Yeah I know, the comment was in general...
  • 0 Hide
    dimaf1985 , December 8, 2008 9:51 AM
    great article. consise and informative at the same time. now if only there was one for amd chipsets...
  • 0 Hide
    marraco , December 8, 2008 11:39 AM
    Good work!.

    Altought, I have an Athlon X2 system, and probably gonna update to a I7 920. It would had be better comparing to an cheap i7 as a reference
  • 1 Hide
    Lurker87 , December 8, 2008 11:59 AM
    Excellent info. It'll be nice having this article to link to.
  • 5 Hide
    antiacid , December 8, 2008 12:34 PM
    This article shows that even in the best conditions, x48 vs p45 is at most 5% difference. Price-wise, this confirms my observations that the lower priced P45 boards are much better performance/value than the x48 premium counterparts.
  • 2 Hide
    Roland00 , December 8, 2008 12:44 PM
    I understand it is more testing, and you already had several months of delays but it would have been nice to see 1920x1200 numbers. 24" monitors are now in the mainstream affordability range with prices ranging from $249 to $349
  • 1 Hide
    waffle911 , December 8, 2008 12:54 PM
    I might be missing something, but it kinda looks like a Phenom 9950 paired with the 790FX SB750 would be comparable to the X48. But really, what am I missing? I can't find a direct comparison anywhere.
  • 0 Hide
    waffle911 , December 8, 2008 1:01 PM
    Sorry: bit of an oversight on my part. CPU charts of course, though the AMD board is using the older SB600, but the performance difference shouldn't be much different.
  • 2 Hide
    Crashman , December 8, 2008 1:03 PM
    Roland00I understand it is more testing, and you already had several months of delays but it would have been nice to see 1920x1200 numbers. 24" monitors are now in the mainstream affordability range with prices ranging from $249 to $349



    You're right! The problem is trying to test a whole bunch of different resolutions. 1920x1200 is almost right in the middle between 1680x1050 and 2560x1600, so hopefully most people can figure out "about" where that resolution would fall on the charts.

    Is it time to get rid of 1024x768? I'm in favor of ditching that resolution and picking a different one.
  • 0 Hide
    FlorinR , December 8, 2008 1:08 PM
    I'm trying to figure out something after reading this article, maybe someone could help me understand??? It seems that a SINGLE Radeon HD 4870 still have enough bandwidth into a PCI-E 1.1 slot, and the differences in performance compared to PCI-E 2.0 came from the chipset (P35 vs. P45 in SINGLE card configuration). Am i wrong?
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