L2 Cache: 4MB or 2MB?

The majority of Intel's Core 2 Duo line feature a single shared 4MB L2 cache, but the E6300 and E6400 are only equipped with a 2MB cache. Given that the Core 2 Duo doesn't have an on-die memory controller, it is more dependent on larger caches than AMD's Athlon 64 X2, which raises the question - how big of a difference is there between the 2MB L2 and 4MB L2 parts?

Our Core 2 Extreme X6800 (2.93GHz) part, like all X6800s, is unlocked so we could simulate any other Core 2 Duo clock speed with it. We managed to get our hands on a Core 2 Duo E6300 (1.86GHz/2MB) and we were in business.

The graph below features all of the benchmarks we ran on the processors in this review, showing the percent performance improvement from a Core 2 Duo E6300 (1.86GHz/2MB) to a hypothetical 1.86GHz Core 2 Duo with a 4MB L2 cache. The bar labeled "Average" is simply an average of all of the performance improvements graphed on the chart.

The 4MB L2 cache can increase performance by as much as 10% in some situations. Such a performance improvement is definitely tangible, and as applications grow larger in their working data sets then the advantage of a larger cache will only become more visible. Unfortunately, you do pay a price premium for this added performance and future proofing as the cheapest 4MB L2 part is the E6600 priced at $316.

If you're the type to upgrade often, then the extra cache is not worth it as you're not getting enough of a present day increase in performance to justify the added cost. However, if this processor will be the basis for your system for the next several years, we'd strongly recommend picking a 4MB flavor of Core 2.

The Test Memory Latency: No Integrated Memory Controller Necessary
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  • Anand Lal Shimpi - Friday, July 14, 2006 - link

    Corrected, it was a misprint.

    Take care,
  • Zorba - Friday, July 14, 2006 - link

    Why is the article talking about how Intel is killing AMD on power consumption when AMD is on the top for both idle and load? If you are doing a performance/watt ratio you need to show that on the graph. This page (page 7) just makes the how article look completely baised.
  • Calin - Friday, July 14, 2006 - link

    Because the EE SFF processors were hard to obtain by Anandtech even for testing purposes. I'm not sure they are available in retail market any more than Conroe is
  • Anand Lal Shimpi - Friday, July 14, 2006 - link

    The Core 2 Extreme X6800 has a performance per watt score of 0.3575 in WME9 compared to 0.2757 for the X2 3800+ EE SFF. I'll put together a performance per watt graph now and see if I can stick it in there.

    Take care,
  • Anand Lal Shimpi - Friday, July 14, 2006 - link

    I included the performance per watt scores I mentioned above in the review now, hopefully that will make things a little more clear.

    Take care,
  • JarredWalton - Friday, July 14, 2006 - link

    I don't see the chart, Anand - I hope I didn't accidentally overwrite your change. Sorry!
  • MrKaz - Friday, July 14, 2006 - link

    Don't put it because it's a biased chart,

    Why based on WM9 benchmark? Why not one of the others?

    Why put it now, if you never put it when A64 was killing the P4s?
  • coldpower27 - Friday, July 14, 2006 - link

    Because AMD didn't real make a big deal about the performance per watt intiative back in the day. They focused on their price/performance instead.
  • MrKaz - Friday, July 14, 2006 - link


    Just because Intel focuses now on that Anandtech must be obliged to put it?

    So for you where was the price/performance (A64 vs P4) charts on Anandtech reviews?
  • coldpower27 - Friday, July 14, 2006 - link

    Yeah, due to their making people aware of it, it has now become a issue.

    It was only after Prescott, that we became more aware that thermals were starting to get out of control and paid more attention to wattage numbers.

    Price/Performance is not as hard to calculate.

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