Latency
As discussed earlier, one of the long term potentials of DDR3 is improved memory latency. To better evaluate whether this is evident with early DDR3 we used the latest version of Lavalys Everest, which is now 4.0. The Memory Latency benchmark was run on both DDR2 and DDR3 test beds at each relevant speed.
Latency test results did not really show us any improvement in the P35 chipset or DDR3. At this early stage of DDR3 the promised latency improvements are not evident. As DDR3 memory speeds increase in the future, and DDR3 memory timings improve, improved latency should be more evident.
We conclude that memory latency is currently all but identical at the same memory speed and timings, whether using DDR2 on P965, DDR2 on P35, or DDR3 on P35. DDR2 cannot yet reach the 1333 speed, while this is an easy target for DDR3. Perhaps higher speed DDR3 and lower timings will allow DDR3 to break away in latency comparisons.
As discussed earlier, one of the long term potentials of DDR3 is improved memory latency. To better evaluate whether this is evident with early DDR3 we used the latest version of Lavalys Everest, which is now 4.0. The Memory Latency benchmark was run on both DDR2 and DDR3 test beds at each relevant speed.
| Everest 4.0 - 2.66GHz Memory Latency in ns - Lower is Better |
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| Memory Speed | P965 ASUS P5B Dlx |
P35 DDR2 ASUS P5K Dlx |
P35 DDR3 ASUS P5K3 Dlx |
| DDR2-800 3-3-3-9 | 64.7 | 63.3 | - |
| DDR2-800 5/6-6-6-15 DDR3-800 6-6-6-15 |
71.2 | 72.7 | 72.7 |
| DDR2-1067 4-4-3-11 | 58.5 | 59 | - |
| DDR2-1067 5/6-6-6-15 | 60.5 | 62.2 | - |
| DDR3-1067 7-7-7-20 | - | - | 63.9 |
| DDR3-1333 9-9-9-25 | - | - | 63 |
Latency test results did not really show us any improvement in the P35 chipset or DDR3. At this early stage of DDR3 the promised latency improvements are not evident. As DDR3 memory speeds increase in the future, and DDR3 memory timings improve, improved latency should be more evident.
We conclude that memory latency is currently all but identical at the same memory speed and timings, whether using DDR2 on P965, DDR2 on P35, or DDR3 on P35. DDR2 cannot yet reach the 1333 speed, while this is an easy target for DDR3. Perhaps higher speed DDR3 and lower timings will allow DDR3 to break away in latency comparisons.
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vaystrem - Tuesday, May 15, 2007 - link
Thank you for your response :)cool - Tuesday, May 15, 2007 - link
What am I missing? How can you have DDR2 800 results for the DDR3 Bearlake mobo?Look at the 3rd row, 4 column of the Sandra benchmarks results on page 5.
TA152H - Tuesday, May 15, 2007 - link
Their chart is a little bit off. It is how they did their best to speed normalize DDR2 and DDR3, so for the DDR2 column for the Bearlake it is DDR2 memory they tested, for the DDR3 version, it is DDR3 memory.It's probably the most useful thing in there, in my opinion. It shows you get extra speed even at the exact same timings, with memory using lower voltage. It's pretty impressive.
cmdrdredd - Tuesday, May 15, 2007 - link
not very impressive to me considering the prices you'll be paying. That's $300 difference between a good DDR2 kit and a DDR3 kit (probably not even high bin or binned at all).TA152H - Tuesday, May 15, 2007 - link
Well, agreed, currently you're not getting much bang for the buck, but that's always the case when new memory comes out. Look at the price of RDRAM, it never got better :P.But, obviously, the prices today mean essentially nothing for the future of the technology, it's just representative of it being a very new technology right now. I'd expect it should be a tiny bit more expensive everything else being equal because some of the additions to it, but it should be insignificant. It's a much cleaner design, and you get some performance on top of it, so I think it's a good technology. I agree, for now, it's difficult to validate the price of it. It's not even like you could say that you're better off getting a DDR3 based design now so you can reuse the RAM. The latencies are so poor on the current stuff you'd probably be aghast at using it a year from now, and you'd probably be able to buy 1 GB of DDR2 today, and 1 GB of DDR3 in a year for less than 1 GB today. So, right now, I don't think it makes much sense to anyone.
Good thing for Intel pushing it though. Anyone that dislikes them needs to recognize how important they are for moving technology forward even at their own cost. Sometimes they've failed though, such as with RDRAM and, so far, EPIC.
Wesley Fink - Tuesday, May 15, 2007 - link
DDR3 will run at DDR3-800 6-6-6-15 timings. We will add this to the DDR-800 5/6-6-6- line to clarify. The point was to run all 3 boards and the two memories at the exact same speed and timings. 800 was the only speed that allowed this.cool - Tuesday, May 15, 2007 - link
Thanks for the explanation, Wesley.I was confused thinking the P5K3 was maybe one of those motherboards that can take 2 types of different RAM, namely DDR2 and DDR3. But that is not the case.
TA152H - Tuesday, May 15, 2007 - link
I see timings of 5/6-6-6-15 and such. What does 5/6 mean? The P965 is running at five and the others at six?Wesley Fink - Tuesday, May 15, 2007 - link
We added this clarification to Page 4 - Memory Test Configuration:"While memory timings were matched to the same memory speed wherever possible, there were a few settings where the chipsets did not allow a direct comparison. DDR3-800 runs at 6-6-6-15 timings. The P965 has options to set 6-6-6-15 timings but the board would not boot under any settings or voltage we fed it at 6-6-6 timings. The closest timings that would work on the P965 at 800 speed were 5-6-6-15. The P5K DDR2 board, based on the P35 chipset, would allow setiing and running 6-6-6-15 timings. This is reflected in our charts with the line ID of 5/6-6-6- for timings. We also tested DDR2 at the fastest timings it could achieve with complete stability on both the P5B Deluxe and P5K Deluxe. This was 3-3-3-9 at DDR2-800 and 4-4-3-11 at DDR2-1066."
TA152H - Tuesday, May 15, 2007 - link
That's clear, I think that will remove any questions relating to the charts.