The Move to DDR3: You Can Do It

The Phenom II 955 and 945 support both DDR3 and DDR2 memory. Just a couple of months ago you could save a good amount of money by going with DDR2 over DDR3, but these days the price difference is negligible.

A good pair of 2GB DDR2-1066 sticks will set you back around $57 while a pair of 2GB DDR3-1333 modules will sell for around $60. The problem is that faster DDR3 modules usually have higher latencies associated with them. The table below shows the CAS latency of these modules in ns:

Memory DDR2-800 DDR2-1066 DDR3-1066 DDR3-1333 DDR3-1600
Data Rate 800MHz 1066MHz 1066MHz 1333MHz 1600MHz
CAS Latency 4 5 5 7 9
CAS Latency in ns 5 ns 4.69 ns 4.69 ns 5.25 ns 5.63 ns

 

From a latency perspective, DDR2 or DDR3-1066 at CL5 is your best bet. However there is a benefit from having more bandwidth; DDR3-1333 delivers 25% more bandwidth but typical DDR3-1333 modules run at CL7 which translates into 12% higher CAS latency than CL5 at 1066.

The chart below shows the performance improvement from running DDR3-1333 (7-7-7-20) vs. DDR2-1066 (5-5-5-15) on the Phenom II X4 955:

In all but two cases the improved bandwidth, but higher latency DDR3-1333 was faster - but the average performance improvement was only 2%. Some applications managed to see a 5 - 6% increase in performance but overall don’t sweat the difference.

Obviously DDR3 is going to do you more good in the long run so it’s what I’d recommend you stick to if you are building a new system. It’s lasted us a long time and we’ve enjoyed its extreme affordability, but DDR2 is finally on its way out.

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  • dragonsphere - Tuesday, July 28, 2009 - link

    I read articles like this all the time for multiple websites. I am a professional application performance tester and I can tell you that most of these articles are junk just to stir up the masses. Most of their statistics are based on averages. This means that 51% of the time they are wrong. Have you noticed that none of them show confidence tests to prove that their data is accurate? Also they don't use 90th percentiles. I think this is due to the lack of the tools that they are using to generate these sub-standard statistics. Until the software they are using is more precise I would consider these tests to be junk science. Reply
  • cal954 - Saturday, May 02, 2009 - link

    Thanks for all the information. I used this model to build my first computer, although no matter what I try to do, my CPU-Z never shows me the multiplier being anything but 4.0 and I can't get my core speed above 800 even w/ CnQ disabled. Reply
  • Hamlet2000 - Saturday, May 09, 2009 - link

    You need to update your bios on your motherboard. I had the exact same thing with my new Phenom II 955 build on a Gigabyte board. Once you update, go into your bios and set the clock at 200 x 16. You'll notice the speed difference right away - it's a smoking fast CPU! Reply
  • Edgemeal - Monday, April 27, 2009 - link

    Geez, some of you people make it sound like AMD has to have the fastest CPU in the market or they just aren't any good or something!

    AMD knows what their chip/PC parts are worth in the market place and their price/performance fits in very nicely. I applaud AMD, without them you'd be reading about the new $900 2GHz P4s right about now LOL!
    Reply
  • swapnadip - Friday, April 24, 2009 - link

    Either AnandTech is Intel fan or Intel pays them hefty Loyalty.

    If not, then why every other reviewieng site shows AMD PHENOM 2 X4 955 BE defeating Core i7 940 on evey computing prospects.

    On some instances it has bashed on Core i7 965 extreme.

    This is pretty much biased and helping INTEL play their MONOPOLOY in this sector. In today's market, no two rivals can have their top of line product bearing differences of Day and Night like shown in this review.

    Thanks
    Reply
  • swapnadip - Friday, April 24, 2009 - link

    Either AnandTech is Intel fan or Intel pays them hefty Loyalty.

    If not, then why every other reviewieng site shows AMD PHENOM 2 X4 955 BE defeating Core i7 940 on evey computing prospects.

    On some instances it has bashed on Core i7 965 extreme.

    This is pretty much biased and helping INTEL play their MONOPOLOY in this sector. In today's market, no two rivals can have their top of line product bearing differences of Day and Night like shown in this review.

    Thanks
    Reply
  • swapnadip - Friday, April 24, 2009 - link

    Either AnandTech is Intel fan or Intel pays them hefty Loyalty.

    If not, then why every other reviewieng site shows AMD PHENOM 2 X4 955 BE defeating Core i7 940 on evey computing prospects.

    On some instances it has bashed on Core i7 965 extreme.

    This is pretty much biased and helping INTEL play their MONOPOLOY in this sector. In today's market, no two rivals can have their top of line product bearing differences of Day and Night like shown in this review.

    Thanks
    Reply
  • iFX - Friday, April 24, 2009 - link

    PII 940 BE = $189.99 on Newegg right now and for the last week+
    PII 940 BE = $189.99 on Newegg right now and for the last week+
    PII 940 BE = $189.99 on Newegg right now and for the last week+
    PII 940 BE = $189.99 on Newegg right now and for the last week+
    PII 940 BE = $189.99 on Newegg right now and for the last week+
    PII 940 BE = $189.99 on Newegg right now and for the last week+
    PII 940 BE = $189.99 on Newegg right now and for the last week+

    ----

    Why is it every AMD article on this site has errors?
    Reply
  • wowo - Friday, April 24, 2009 - link

    how x264?x264 benchmark 2.0 is very old .

    it is 819,but new x264 is 1139.intel is better for 1139 a lot.

    please test wirh new x264.
    Reply
  • ultrageek1111 - Friday, April 24, 2009 - link

    you know what they say about black processors... Reply

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