DDR3 vs. DDR2

by Wesley Fink on May 15, 2007 2:40 PM EST
Conclusion

The purpose of this comparison of DDR3 and DDR2 was to determine whether DDR3 really brought any better performance to the Core 2 platform. However, the test was designed so that any performance improvements that were brought by the new P35 (Bearlake) chipset would be captured and could be isolated. P35 supports either DDR2 or DDR3, and we found no real difference in current performance of DDR2 and DDR3 on the P35 platform. Both were equally faster than the same DDR2 on the P965 chipset.

That means the real performance surprise in these tests is that the revised memory controller in the Bearlake chipset improves buffered memory bandwidth by 16% to 18%, with a real-world improvement in gaming and application performance of 2 to 5%. This is a pretty impressive improvement for a memory controller update. To repeat an old saying please remember that memory is just one small part of the system, so a 2% to 5% increase in gaming from the memory controller alone means the P35 memory controller is significantly improved over the P965 chipset.

DDR3 at introduction is saddled with pretty dismal memory timings. As you can see in our test bed chart, SPD timings are 6-6-6-15 at DDR3-800, 7-7-7-20 at DDR3-1066 and 9-9-9-25 at DDR3-1333. Despite the slower timings DDR3 runs at higher speeds than any DDR2 we have tested, and we will have official JEDEC timings for DDR3 to 1600 with the current JEDEC standard, and possibly ever faster with any future JEDEC update.

Even at slow timings, DDR3 shows a great deal of promise. It is as fast as very fast DDR2 on the P965, but it can't match the same DDR2 memory performance on the P35. DDR3 can run at higher speeds than DDR2 and as faster memory timings inevitably appear DDR3 will be the right choice for computer enthusiasts looking for the best performance. While we can't prove better latency or significantly better performance with the slow timings of launch DDR3, the evidence is all there in these tests. DDR3 will get faster in speed and will provide the best performance in the long term.

That brings up the more difficult question: what to buy today? That is a much more complicated question. If you are looking for a new system, definitely choose the new P35 chipset over the P965, as it is a better memory performer. At launch we are told DDR3 will be much more expensive than DDR2. Prices are expected to be about $480 for a 2GB DDR3 kit. At that lofty price it is difficult to recommend DDR3 over DDR2, when DDR2 performs just the same on the P35 chipset and decent 2GB kits can be had for under $150 now.

Two conditions would shift the recommendation to DDR3 instead. When DDR3 prices come close to DDR2 then buy DDR3 instead. More significantly, when DDR3 becomes available at higher speeds and/or faster timings then definitely choose DDR3 if you are looking for performance - even if the price is higher.

We asked many memory vendors when they thought price parity and fast DDR3 timings might be available. The more skeptical said not until late 2008, while the more optimistic felt it would happen by the end of 2007. Until either or both events happens there is no compelling reason to buy DDR3. However, there is no doubt at all that DDR3 is in your future as the top-performing memory you can buy. Some will also buy it because it is the future and they can likely carry their DDR3 supporting board a little further into the future.

AMD's launch of their Phenom processors will also be something to consider for it's potential impact on DDR3 adoption. Phenom will initially launch with DDR2 only. If AMD can regain the performance crown, the shift to DDR3 may be further delayed, just like what happened with the DDR to DDR2 shift.

The winner for now is the P35 chipset, whether you feed it DDR2 with fast timings or higher speed DDR3. The 1333 bus speed introduced by P35 is also a winner - at least in terms of overclocking. As stated in the review, almost every Core 2 Duo and Core 2 Quad we tried in the P35 ASUS P5K and P5K3 ran at 1333 FSB at the default multiplier and default voltage. The only processors that required any voltage increase were the top line Core 2 Extreme processors. This free 25% overclock, which still allows everything else in the system to run at default values, is exciting. It is so exciting we have to wonder how long Intel will allow this in the marketplace.

DDR3 may not be in your buying plan today, but it will certainly be there in the future. As DDR3 prices drop and/or timings improve, it will be the performance choice. For today, the best performance choice is either today's DDR2 or tomorrow's DDR3 on the P35 chipset instead.

Number Crunching and Gaming
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  • Final Hamlet - Tuesday, May 15, 2007 - link

    Oh look! It's Bicycle repair man!
  • just4U - Wednesday, May 16, 2007 - link

    I don't really know what to think with ddr3 .. or even ddr2.

    When I jumped from PC 2700 memory (cas 3 i think) up to PC3200 memory cas 2 I noticed a increase in the overall speed of my computer.

    When I jumped to DDR2 PC5300 I noticed no speed increase. When I jumped to PC6400 I noticed no speed increase. When I overclock my memory I notice no...

    You get the picture.

    I have a question. DDR3 with tight timings, Will we accualy notice it over ddr2? Or will it be one of those things where only a benchmark tends to notice anything.
  • Starglider - Friday, May 18, 2007 - link

    Depends on what applications you're running. But based on your recent experience, probably not.
  • defter - Tuesday, May 15, 2007 - link

    The article says that P965 board was running at 1066MHz FSB and then writer is suprised when P35 + DDR2 running at 1333MHz FSB is slightly faster??? Then in the conclusion it's said that the reason for an increased performance is the chipset instead of a higher FSB???

    If you want to make P965 vs P35+DDR2 comparision, why not use the same FSB.....
  • Wesley Fink - Tuesday, May 15, 2007 - link

    The P965 was running at 10x266 or 2.66GHz. The P35 boards ran at 8x333 or 2.66GHz. 1333 is not a natural CPU ratio on the P965 so when you choose 1333 there is no way to also choose DDR2-800. At 1333 the closest you can get (at a different strap) is 833. We believe the way we tested was as close to apples to apples as we could design. Remember we are looking at MEMORY PERFOMNACE, and the FSB should not matter as long as memory speed and timings are set the same on all test boards, which we definitley insured.

    Despite that, we know that Sandra XI results can be influenced a small amount by CPU speed and possibly FSB. To make sure our results were still as close to apples to apples as possible we did run 10x266 on all boards and compared results to our test setup. The MEMORY PERFORMANCE results were virtually the same as we have reported.

    We do agree that were we testing CPU performance the differing bus speeds at the same resulatant CPU speed could make some difference.
  • IntelUser2000 - Wednesday, May 16, 2007 - link

    quote:

    Despite that, we know that Sandra XI results can be influenced a small amount by CPU speed and possibly FSB. To make sure our results were still as close to apples to apples as possible we did run 10x266 on all boards and compared results to our test setup. The MEMORY PERFORMANCE results were virtually the same as we have reported.


    Defter is right. You guys were just testing performance increase by using a 1333FSB instead of 1066FSB. Memory bandwidth tests like Sandra will show HUGE differences. Remember, the CPU will not benefit from faster memory when FSB isn't faster. It's different from AMD where Hypertransport is only used for northbridge to southbridge communications(which yields into 0% improvement ) for PC.
  • Wesley Fink - Wednesday, May 16, 2007 - link

    P35 is a combination of an increase in bus speed to 1333 and an improved memory controller. We are working on a followup article to appear in a few days that shows the breakdown of the bus speed contribution and the memory controller contribution.

    That does not change the fact that memory bandwidth for P35 is improved 16% to 18% over P965, but we have run additional tests to show the individual impact of the bus speed increase and the memory controller improvements.

    In approaching testing it is not possible to run 1333 FSB on the P965/975x and also run memory speeds like 800 and 1066 as we would like. On P35 if 1066 FSB is selected then 1333 is not available as a memory option. We can, however, run 1066 FSB on P35 to roughly determine Memory Controller contribution compared to P965, and then compare those results to 1333 equivalents (8X333 instead of 10x266) to see the additional impact of the 1333 bus on memory performance. Those results will be reported as soon as testing is complete.
  • defter - Wednesday, May 16, 2007 - link

    quote:

    1333 is not a natural CPU ratio on the P965 so when you choose 1333 there is no way to also choose DDR2-800


    Why not report results at 1066MHz FSB then?


    quote:

    Remember we are looking at MEMORY PERFOMNACE, and the FSB should not matter as long as memory speed and timings are set the same on all test boards, which we definitley insured.


    Intel's CPUs are FSB limited since memory traffic goes through FSB. For example, 1066MHz FSB can transfer 8.5GB/s while dual channel DDR2-800 can provide 12.8GB/s. Thus, increasing the FSB also affects memory performance.
  • vaystrem - Tuesday, May 15, 2007 - link

    I'm curious:
    A) Why did you chose Farcry?
    B) Why you didn't include more game tests?

    I think it would be particularly interesting to see how a game like Supreme Commander or Company of Heroes performs. In strategy games you have the stress from the graphical component and a heavy AI load which may take better advantage of all that bandwidth than a simple FPS.
  • Wesley Fink - Tuesday, May 15, 2007 - link

    This was a comparison of DDR3 and DDR2, not a launch review for P35. You will see that when the performance embargo lifts on May 21st. Far Cry is part of our standard memory test suite and we are very familiar with how it behaves with variations in memory bandwith and timings. That is why it was chosen.

    You will see test results with many more games when we review the chipset on May 21st and the new P35 motherboards on June 4th.

    Consider this a preview, and all the advance info we could give you at this point. The NDA for DDR3 memory has lifted, but the performance NDA for P35 is in place until the 21st.

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