Intel's plans for higher Front Side Bus frequencies come as no surprise to those that have been carefully reading for years now. Back in October of 2001 we outlined Intel's FSB targets for the major core releases of the coming years:

"Although not nearly as high, FSB frequencies are also ramping up as clock frequencies do. Intel's Northwood (0.13-micron Pentium 4) core will eventually use a 533MHz FSB, Intel's Prescott core will use a 800MHz FSB, and their Tejas core will use an incredible 1.2GHz FSB upon its release."

Things have obviously changed since we made that statement, primarily that Tejas has since been canceled and Intel introduced an Extreme Edition of the Pentium 4 based on the Gallatin Xeon core. Given the revised plans, what do present day roadmaps say about Intel's FSB targets for the future?

Today Intel is making the move from 800MHz up to the 1066MHz FSB, with the release of the Pentium 4 3.46 Extreme Edition. Priced at $999, the 3.46EE will be followed up by the 3.73EE as the only two chips to support the faster FSB for almost a year. Current Intel roadmaps show absolutely no support for the 1066MHz FSB from any processor other than the two aforementioned Extreme Edition chips until the end of next year, when Prescott-2M chips will finally receive 1066MHz FSB support; there are also plans for dual core 1066MHz FSB chips although they have not been publicly outlined on any roadmap.

It seems as if Intel isn't interested in releasing a new revision of their mainstream chipsets and wants to thus save the move for Prescott to 1066 for their upcoming Lakeport chipset. What that means is that today we are seeing a very limited launch of a new FSB as a feature exclusive to the Extreme Edition CPUs, no doubt a way of adding more value to the very expensive Extreme Edition offering.

The faster FSB is enabled through a revision to the 925X chipset called the 925XE. The 925XE simply adds 1066MHz FSB support, and nothing more, to the feature set of 925X. By enabling 1066MHz FSB support, the 925XE chipset can finally run the FSB and DDR2-533 memory buses synchronously, offering a balanced 8.5GB/s of bandwidth over each bus while operating at multiples of the same base 266MHz frequency. The end result is that the 1066MHz FSB should guarantee lower latency memory accesses for any chip that uses it with DDR2-533. However it seems that Intel paired the faster FSB with the worst possible choice out of their processor line; armed with an on-die 2MB L3 cache, the Pentium 4 Extreme Edition already has the lowest latency memory accesses out of the entire Pentium 4 line, thus softening the impact of the synchronous 1066MHz FSB.

The other thing to keep in mind is that faster FSB frequencies truly become beneficial as higher CPU speeds cause the bus to saturate with data requests and transfers - strike 2 against Intel's choice of introducing the FSB with the Extreme Edition. Prescott continues to be the higher clocked CPU (not to mention the deeper pipelined CPU of the two), thus making it the better candidate of the two for the 1066MHz FSB.

While some have speculated that Prescott isn't yielding well at the 1066MHz FSB, it would seem that the reasons for not moving Prescott to 1066MHz are much more marketing related. The current 915 and 925X chipsets are not selling well at all and the thought of replacing both of those chipsets with new, 1066MHz FSB versions (especially the high quantity mainstream 915 chipset), so that Intel could migrate the entire Prescott line to the 1066MHz FSB wouldn't go over very well with the motherboard manufacturers. From talking with numerous motherboard manufacturers it would seem that Intel is trying to save any major performance improvements for their upcoming Glenwood/Lakeport chipsets, in order to avoid what happened with 925X/915P where there was no performance improvement over the previous generation of chipsets. This may also be why there is no talk of 1066MHz FSB Pentium 4s on Intel's current roadmaps, all conversation about the future 1066MHz FSB parts appears to be happening over telephone and face-to-face meetings only, the former of which we have been privy to upon numerous occasions recently. It could very well be that even Intel is unsure about what their future 1066MHz FSB plans will be at this point.

We shouldn't eliminate the possibility that Prescott may not be yielding well at the faster FSB. Remember that the major limitation to FSB frequency is CPU packaging, the connection and routing of signals from the solder bumps on the silicon core to the pins (or in this case pads) on the chip itself. It could very well be that Prescott's 7-layer design has a correspondingly more complex packaging layout, resulting in some present day hurdles to increasing FSB frequency. That being said, we have heard more reports of people being able to run their Prescott CPUs at the 1066MHz FSB than those that haven't. Take that for what it's worth.

The Pentium 4 3.46EE replaces the 3.40EE as the fastest Extreme Edition CPU from Intel. However with only a 66MHz clock speed advantage, we would expect almost all of any performance increase we see to be caused by the 1066MHz FSB. But how much performance can we expect from a FSB increase on a processor that isn't the best choice for a FSB increase? Given the simplicity of today's launch (just one slightly faster chip with a slightly modified chipset), let's just find out.

Does the 1066MHz FSB Improve Memory Performance?


View All Comments

  • T8000 - Thursday, November 4, 2004 - link

    The most important part of this release is the Intel 925XE chipset, that will allow much higher overclocks because of its 1066 bus support.

    This is because the 925XE will have the right divider to reach 1066 without any PCI-E overclock.

    So with a 925XE mainboard, you can run an Intel 530 CPU at 4Ghz with any PCI-E GPU you choose, because only the CPU will be overclocked and Prescott has excellent chances of reaching 4Ghz with modest water cooling or good air cooling.
  • Odeen - Wednesday, November 3, 2004 - link

    Realtek codec on an Intel board... and here I thought Intel actually made quality motherboards, which entails Sigmatel or Soundmax onboard audio chips.

    Sigh :(
  • johnsonx - Wednesday, November 3, 2004 - link

    Slim: You're right... my bad. I didn't read every single page. I read the couple of introductory pages, then skipped to the test configuration page, perused a few benches, and then skipped to the conclusion.

    The measured results of course are no different than I thought they would be...
  • bob661 - Tuesday, November 2, 2004 - link

    We need to have our own review website called www.dontreleasesh!tunlessitsactuallyabetterproductthan Reply
  • SLIM - Tuesday, November 2, 2004 - link


    Anand did isolate the fsb as the sole variable when he DOWNclocked both chips to 3.2ghz (266 x 12 and 200 x 16) on page 3. There was a slight caveat that faster chips would benefit more from a fsb boost. And yes the faster bus increased performance by almost 1% in some tests woohoo!!!

  • johnsonx - Tuesday, November 2, 2004 - link

    One thing that might've been interesting to see:

    Overclock the 3.4EE to 3.46Ghz by OC'ing the FSB to 203Mhz or 204Mhz (812 & 816 respectively). This would completely isolate the effect if the increased clock speed of the 3.46EE, showing only the increased FSB performance... at that point I suspect that the tiny performance gains would completely evaporate.

    Mind you, I'm not suggesting this would change the conclusion much, but it would put a big exclamation point to it...

    BTW, one does have to wonder why Intel bothered with this. If the 3.46EE/925XE combo is no faster than the 3.4EE/925X combo (I'm assuming the 925X=925XE @800FSB), then why go through all the trouble? Indeed, isn't it true that an 'old' 3.4EE/875 combo is faster still?

    Good grief, at least when AMD releases a new top-end chip it is actually measurably faster. Regardless of whether the rating is 'earned' or not, no one can argue that the 4000 isn't (generally) faster than the 3800, nor that the FX-55 isn't faster than any other A64.
  • Tides - Tuesday, November 2, 2004 - link

    Some benchmarks? Hardly. AMD owns in actual games, workstation apps, and half of the other stuff. Not to mention AMD doesn't make you upgrade to ddr2, and AMD cpus are 64bit. Intel's new chips have low shelf lives while the current AMD 64's you buy will last you a lot longer.

    Performance, realiability, and long lasting.
  • danidentity - Tuesday, November 2, 2004 - link

    IntelUser2000, you couldn't possibly be any more wrong. I will be the first to admit that AMD chips excel above Intel chips in many benchmarks.


    1. Intel is no where near dead. Calling them so is ridiculous. In Q3 of this year Intel posted revenue of 8.5 billion compared to AMD's 1.2 billion, or SEVEN times as much.

    2. AMD is NOT closing "very rapidly" in marketshare. It would appear that way from reading sites and forums like these, but it gives you a false impression. Keep in mind that the largest supplier of PCs on the planet puts Intel chips in every machine. AMD's mobile chips can't compete with the Pentium M in terms of performance and functionality.

    3. Intel is not stupid, they have some of the best engineers on the planet. If they seriously thought that AMD was going to topple them as the market leader, or even if they are predicting it, you can GUARANTEE they have something in the works to strike back. They have the means and the money.

    4. While many people don't know exactly what clockspeed is, everyone thinks it is the ultimate measure of performance. That mindset will take a LONG time to change, and by then, Intel will have something new.

    Most people out there don't even know AMD exists. Just because AMD chips beat Intel chips in some benchmarks posted on technical computer sites, don't mean they're going to topple Intel.
  • JonahStone - Tuesday, November 2, 2004 - link

    Performance is not the only reason why somebody buys a CPU. Although 64 bit might not be available now, does not make it unimportant. Many who buy a computer will keep it for a long time. I do not want to buy a new PC in a year's time to run 64 bit apps. All reviews keep on comparing 32 bit performance and do not even mention the advantage 64 bit will bring. It does matter!!!!!!! Reply
  • IntelUser2000 - Monday, November 1, 2004 - link

    Intel is not doing bad. They are doing terrible. So terrible that you might as well call them dead. Probably will last till 2009 before they fill bankruptcy.

    To those people who say people in forums don't know anything and that there are other people stupid enough to buy Intel chips(I mean all Intel chips): Uhh, yeah, get your head straight, since AMD is closing with Intel very rapidly in marketshare, in server, desktop, and laptop, and that means that gamers actually do make a difference(albeit slowly) making other people buy computers. You think other people will buy P4's because of high clock speed? That's BS, since people who is stupid enough to buy Intel chips don't even know what clock speeds does. There are only a very few that knows computers JUST enough to say clock speed is good.

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