DDR3 vs. DDR2

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

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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  • Wesley Fink - Tuesday, May 15, 2007 - link

    Yes. The P965 would not boot witha a CAS setting of 6 even though it could be selected. So the P965 was tested at 5-6-6 timings. The same DDR2 on the P5K was tested at 6-6-6, which would work and also matched the DDR3 timings. We will clarify this in the article.
  • TA152H - Tuesday, May 15, 2007 - link

    OK, thanks.

    One thing I would suggest when you do the final tests for the Bearlake and DDR3 is to use the 2M processors as well. You'd expect the 4M cache to hide the differences better, obviously, so the 2M cache processors would be pretty interesting to see as well, if for no other reason to see how much the larger cache does mask the difference in the chipset and memory. Since Intel is planning on increasing cache sizes, it would be a pretty useful data point.
  • TA152H - Tuesday, May 15, 2007 - link

    You measured the performance of the memory, but why not take a power measurement of it as well. That is one of the draws of the technology, it uses lower voltage, and therefore should use a little less power and generate less heat. Both are significant.

    Good article though, I just wish that had been included.
  • kalrith - Tuesday, May 15, 2007 - link

    Page 2, second line of second-to-last paragraph says, "which is a 16% reduction form DDR2". "form" should be "from".

    Last page, fourth line of third-to-last paragraph says, "the shift to DDR2 may be further delayed". "DDR2" should be "DDR3".

    BTW, I found the article interesting, informative, enlightening, and unbiased (as usual).
  • Wesley Fink - Tuesday, May 15, 2007 - link

    Mild dyslexia and less-than smart built-in spell checkers always win :) Both errors are corrected. Thanks.

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