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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  • crystal clear - Saturday, July 15, 2006 - link

    Just to remind all that-" Intel decides to release a B2 stepping of its Conroe
    processors.Also
    BEWARE of Engineering samples & reviews based on Engineering samples inlcuded.
    Reply
  • OcHungry - Saturday, July 15, 2006 - link

    I don’t know if this Q been asked or answered (sorry no time reading 120 posts)
    Bu Mr. Anand, can I kindly ask you couple of concerns:
    1) why don’t we see any reference to temp. under load? Temp. is a crucial factor in deciding wether or not I buy conroe since I live in a very hot climate.
    2)A lot people make reference to 64bit and window vista and that conroe is a 32bit architecture and will not perform as good in 64bit. Is it true? can we have some 64bit benchmarks? It would be great to do this test in multitasking.
    3) I have also noticed (from so many who have had pre-release ES @ XS, and other forums) that overclocked conroe does not correspond directly to performance, unlike A64.
    What I mean is: If A64 is overclocked 20%, the performance increases ~20% 9more or less, in most cases), But have not seen this to hold w/ conroe. So I am wondering what would happen if we put a low end conroe, such as E6400 against A64 4000 x2, 2x1mb cache (same price range after price drop) and overclock them to their limit, using stock cooling, and do the benchmarks (64bit included). The reason I am interested in this type of review is because I am an average end user on budget and would like to know which would give me better price/performance. I think I am speaking for at least 90% of consumers. Not everyone buys $1000 cpu and consumers on budget is detrimental to survival of conroe or AM2 cpus. This alone should give you enough incentive to put together a review oriented around us, the mainstream computer users. We can make or break any chipmaker.
    So please Mr. Anad, can we have another review along those lines described above?
    We greatly appreciate it.
    Thanks,
    ochungry
    Reply
  • aznskickass - Saturday, July 15, 2006 - link

    Hey ochungry, I believe Xbitlabs did an overclocking comparison between a Conroe E6300 and an A64 X2 3800+, and while they didn't do any 64bit benchmarks, the conclusion is that at stock speeds the E6300 is slightly faster than X2 3800+, and when both are overclocked to the max, E6300's lead increases even more.

    Here is the review/comparison:
    http://xbitlabs.com/articles/cpu/display/core2duo-...">http://xbitlabs.com/articles/cpu/display/core2duo-...
    Reply
  • OcHungry - Saturday, July 15, 2006 - link

    Those guys @ X-bit lab do not fool me. And I hope Anandtech conducts the same test w/ best suited memory module for “BOTH” platforms. We know (so as Xbitlab knows) that, because of IMC, A64 performs its best @ tightest memory timings. X-bit lab should have used http://www.newegg.com/Product/Product.asp?Item=N82...">This memory module if the test was going to be fair and square. Furthermore A64 3800 x2 @ 3ghz is 10x300, which means DDR2 667 1:1 could have been better to use. This http://www.newegg.com/Product/Product.asp?Item=N82...">DDR2 667 @ 3-3-3-10 would have given about 10% better performance than DDR2 4-4-4-12 that they used. X-bit does not mention anything about memory/cpu ratio. What divider was used? Was it 133/266? Or as close to 1:1 as possible? Sooner or later the truth will prevail when we end users try it for ourselves (oh BTW, not ES), and we will see if xbitlab and others were genuinely interested on behalf of consumers, or the interest destined to ill-fated purpose. Will not accuse anyone, but it all look very fishy.
    I am certain that Mr. Anad will clear all these conspicuous reviews , and hand us another that concerns the consumer’s majority- us average users.
    Reply
  • IntelUser2000 - Saturday, July 15, 2006 - link

    quote:

    We know (so as Xbitlab knows) that, because of IMC, A64 performs its best @ tightest memory timings. X-bit lab should have used This memory module if the test was going to be fair and square. Furthermore A64 3800 x2 @ 3ghz is 10x300, which means DDR2 667 1:1 could have been better to use. This DDR2 667 @ 3-3-3-10 would have given about 10% better performance than DDR2 4-4-4-12 that they used.


    W-R-O-N-G!!! DDR2-800 at EVEN slower 5-5-5-15 timings is FASTER THAN DDR2-667 3-3-3-10: http://xbitlabs.com/articles/cpu/display/amd-socke...">http://xbitlabs.com/articles/cpu/display/amd-socke...

    Prefer AT's results?: http://www.anandtech.com/cpuchipsets/showdoc.aspx?...">http://www.anandtech.com/cpuchipsets/showdoc.aspx?...

    DDR2-800 is faster. The myth that it performs amazingly better(comparatively) with lower latency is just, a myth. I believe there was a thread in forums that tells exactly that.
    Reply
  • OcHungry - Sunday, July 16, 2006 - link

    Iguess you don’t understand much about AMD's memory latency, direct connect, and 1:1 ratio.
    It is not like Intel's illusionary, that faster than FSB is better. It is not and is useless. Anad proved it here. But this subject has a tendency to be dragged on for ever by those who don’t understand the concept of IMC. So it's better leave it alone.
    But I still would like to see tightest timing and 1:1 ratio. It is now clear to me that those reviews in favor of Intel, artfully evade this argument/request, knowing it will give AMD advantage over Intel's FSB.
    Reply
  • aznskickass - Sunday, July 16, 2006 - link

    *sigh*

    How is the AMD disadvantaged if BOTH platforms are reviewed using the same RAM?

    AMD needs ultra low latency DDR2 to attain best performance? Well, bad luck, Intel doesn't , there is no 'deliberate' conspiracy to put AMD in a bad light.

    Look, if you just want to hang on to the notion that AMD has been cheated in the reviews, then go ahead and get your X2 4200+ and see how close you can get to Conroes numbers.

    I'll be using my E6600 @ 3.5GHz+ and laughing at your stupidity.
    Reply
  • aznskickass - Saturday, July 15, 2006 - link

    I consider Xbitlabs to be one of the more trustworthy sites around, and do note that they are testing mainstream chips, and expensive CL3 DDR2 just doesn't make sense in a budget setup, which further puts Conroe in a good light, as it doesn't require expensive CL3 DDR2 to perform well. Reply
  • sum1 - Friday, July 14, 2006 - link

    A good read. For the editor, I found 4 errors, search the full lines of text below at:
    http://www.anandtech.com/printarticle.html?i=2795">http://www.anandtech.com/printarticle.html?i=2795

    That begin said,
    and H.264 in coding
    as soon as its available
    at the fastest desktop processor we've ever tested
    ("and" would be more readable that "at" in this sentence)
    Reply
  • JarredWalton - Friday, July 14, 2006 - link

    Thanks. At least one of those (in coding) can be blamed on my use of Dragon NaturallySpeaking and not catching the error. The others... well, they can be blamed on me not catching them too. LOL. The last one is sort of a difference of opinion, and I've replaced the comma with a dash, as that was the intended reading. :)

    --Jarred
    Reply

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