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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  • finbarqs - Friday, July 14, 2006 - link

    just to show you how EASY it is to O/C the system! (and for the Futuremark junkies :-) )

    http://www.futuremark.com/forum/showthread.php?p=1...">http://www.futuremark.com/forum/showthread.php?p=1...

    You would want one :)

    if you want to know, 3DMark 2001SE posted a score of 45k, and 3DMark 2003 posted a 33k, FACTORY.
    Reply
  • phaxmohdem - Friday, July 14, 2006 - link

    I was wondering if you could possibly do some "single core" performance testing in the CPU's by simply changing the HAL to "ACPI Uniprocessor PC" instead of "multiprocessor PC" This would tel windows to only use one of the Core2 Duo cores, and I think would give us a good indication of how it will perform when released. Especially on the 2MB cache models, since I'm guessing the single cores won't bust out the door with a full 4MB.

    Just some food for thought/consideration. I personally would love to see a few tests run this way and compared to some single/dual core A64's.
    Reply
  • JarredWalton - Friday, July 14, 2006 - link

    Conroe-L is so far off that it's really an afterthought. The only reason it's not shipping is that Intel has a ton of Netburst stuff to offload, IMO. At $145, the PD 945 is still interesting in terms of certain computational tasks. (I miss the QMD Folding@Home cores....) Reply
  • fishbits - Friday, July 14, 2006 - link

    I had hoped AMD could gain even more market-share before something like this happened, would rather see the two CPU makers on more even footing. Intel just hit this one out of the park however, if pricing holds and availability is decent. Was looking at upgrading my 3500 (939) to a $300 X2 4600 after the price drop, but now? It looks like I'll probably keep this system and build a new rig around a $300 Intel 6600, which wins over or smokes the 4600 depending on benchmark. I really don't know what AMD can do to keep me in the short term, because I don't know if they can make any money dropping prices as far as it looks like they'll need to go. Reply
  • SpaceRanger - Friday, July 14, 2006 - link

    One thing to consider though, if you decide to go with the C2D 6600, then you will also have to spend $$ on a new Mobo + Memory (since your DDR RAM won't work on the platforms for C2D. Keep that in mind when you're upgrading. Reply
  • fishbits - Saturday, July 15, 2006 - link

    When I said that if I went with Intel I'd keep my current rig and build a new one around the Conroe, didn't it dawn on you that I'd already "considered" the need to get a new mobo, memory, etc? Reply
  • SpaceRanger - Sunday, July 16, 2006 - link

    Holy arrogance.. EXCUSE ME for pointing something out.. Reply
  • epsilonparadox - Friday, July 14, 2006 - link

    Well the loads of money they made when they had the better performing architecture can hopefully keep them doing very well also the Opteron isn't really being challenged and thats really their moneymaker right now. They shouldn't have any problems lowering prices on their desktop chips while keeping the status quo on the Opterons. Reply
  • zsdersw - Saturday, July 15, 2006 - link

    They can't really keep the status quo on the Opterons either. Woodcrest excels (or, at the very least, is equal to the Opteron) in the 1P and 2P server space.. which is a huge chunk of the overall server market. Reply
  • LoneWolf15 - Friday, July 14, 2006 - link

    While I'm sad to see AMD lose the performance crown, I'm not so obtuse as to deny it's happening.

    I'm excited by Intel's newest chip, but I think the results for me will be that I'll buy a faster Athlon 64 X2 when the prices drop (assuming Socket 939 ones become cheaper as well, I don't plan a move to Socket AM2 for some time to come). So Intel's newest chip should benefit even those of us sticking with an AMD system. :)
    Reply

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