First Look: AM2 DDR2 vs. 939 DDR Performance
by Wesley Fink on April 17, 2006 12:05 AM EST- Posted in
- CPUs
Final Words
When the article OCZ EL PC2-8000 XTC: Low Latency PLUS DDR2-1100 was posted a couple of weeks ago, the potential of this incredibly fast DDR2 memory on the upcoming AM2 platform was clear. What was not expected was that the opportunity to run the DDR2-1000 memory through its paces on an AM2 was only a couple of weeks away. After looking more closely at DDR2 memory performance on the 4th spin of the AM2 processor it is clear AMD will definitely be able to launch AM2 with the expectation of better performance than the Socket 939 it replaces. This avoids one of the huge pratfalls that plagued Intel in their move to DDR2.
However, the memory bandwidth increases of up to 30% on AM2 and the Latency improvements of 12 to 16% compared to the fastest DDR memory on socket 939 do not yield much in real-world performance. The real-world performance increase for AM2 compared to Socket 939 will likely be very small - in the range of no increase to about 7%, depending on the application.
In normal times this would be great news! In times where previews of Intel's new Conroe architecture show solid 20%+ improvements in performance compared to AMD Socket 939, these smaller AM2 increases are reason for concern. It certainly appears that unless some unforeseen miracle happens, the move from Socket 939 DDR to AM2 DDR2 just can't generate anywhere near the performance improvement AMD really needs to combat Intel's Conroe. This article evaluated memory and gaming performance, but you can see comparisons of General Performance, multimedia and encoding in the companion article AMD Socket-AM2 Performance Preview.
Not all is gloom in the AMD camp, however, as there are certainly bright spots. AM2 IS faster than Socket 939, with even more possible DDR2 bandwidth for the future. Unfortunately, unless AMD makes revisions to the core and/or adds more cache with the 65nm die-shrink there is not much improvement from the move to AM2. The extra bandwidth and lower latency just don't translate into meaningful performance improvements with today's applications.
There are also a few general observations about using DDR2 with the new upcoming AM2. Using fast, top-line memory DDR2-533 is roughly equivalent in bandwidth to fast DDR400 memory. That observation should also hold with mainstream memory where DDR400 3-3-3 should perform about like DDR2-533 4-4-4. Most memory manufacturers will also be producing fast high-end DDR2-800 and more mainstream DDR2-667 and DDR2-800 parts for launch with AM2, so there will likely be many more memory choices when AM2 launches.
Last, the move to a unified memory specification with Intel will likely be a good development for those looking to buy new DDR2 memory. With AMD and Intel both using DDR2 there will likely be more innovation in the DDR2 market, more choices, and even better prices. Add to that the expectation that both AM2 and Conroe will launch with official DDR2-800 support and faster DDR2 memory should be much easier to find and afford in the near future.
It appears AMD will succeed in launching a faster on-processor DDR2 memory controller. The latest AM2 pre-release samples are showing significant improvements over Socket 939 DDR in both memory bandwidth and latency. Unfortunately, the current AMD architecture running current applications and games doesn't appear to need the additional bandwidth or reduced latency. This may change in the future, but for now the move to AM2 and DDR2 memory looks like it will yield far too little in performance improvements to keep AMD competitive in the upcoming desktop marketplace.
When the article OCZ EL PC2-8000 XTC: Low Latency PLUS DDR2-1100 was posted a couple of weeks ago, the potential of this incredibly fast DDR2 memory on the upcoming AM2 platform was clear. What was not expected was that the opportunity to run the DDR2-1000 memory through its paces on an AM2 was only a couple of weeks away. After looking more closely at DDR2 memory performance on the 4th spin of the AM2 processor it is clear AMD will definitely be able to launch AM2 with the expectation of better performance than the Socket 939 it replaces. This avoids one of the huge pratfalls that plagued Intel in their move to DDR2.
However, the memory bandwidth increases of up to 30% on AM2 and the Latency improvements of 12 to 16% compared to the fastest DDR memory on socket 939 do not yield much in real-world performance. The real-world performance increase for AM2 compared to Socket 939 will likely be very small - in the range of no increase to about 7%, depending on the application.
In normal times this would be great news! In times where previews of Intel's new Conroe architecture show solid 20%+ improvements in performance compared to AMD Socket 939, these smaller AM2 increases are reason for concern. It certainly appears that unless some unforeseen miracle happens, the move from Socket 939 DDR to AM2 DDR2 just can't generate anywhere near the performance improvement AMD really needs to combat Intel's Conroe. This article evaluated memory and gaming performance, but you can see comparisons of General Performance, multimedia and encoding in the companion article AMD Socket-AM2 Performance Preview.
Not all is gloom in the AMD camp, however, as there are certainly bright spots. AM2 IS faster than Socket 939, with even more possible DDR2 bandwidth for the future. Unfortunately, unless AMD makes revisions to the core and/or adds more cache with the 65nm die-shrink there is not much improvement from the move to AM2. The extra bandwidth and lower latency just don't translate into meaningful performance improvements with today's applications.
There are also a few general observations about using DDR2 with the new upcoming AM2. Using fast, top-line memory DDR2-533 is roughly equivalent in bandwidth to fast DDR400 memory. That observation should also hold with mainstream memory where DDR400 3-3-3 should perform about like DDR2-533 4-4-4. Most memory manufacturers will also be producing fast high-end DDR2-800 and more mainstream DDR2-667 and DDR2-800 parts for launch with AM2, so there will likely be many more memory choices when AM2 launches.
Last, the move to a unified memory specification with Intel will likely be a good development for those looking to buy new DDR2 memory. With AMD and Intel both using DDR2 there will likely be more innovation in the DDR2 market, more choices, and even better prices. Add to that the expectation that both AM2 and Conroe will launch with official DDR2-800 support and faster DDR2 memory should be much easier to find and afford in the near future.
It appears AMD will succeed in launching a faster on-processor DDR2 memory controller. The latest AM2 pre-release samples are showing significant improvements over Socket 939 DDR in both memory bandwidth and latency. Unfortunately, the current AMD architecture running current applications and games doesn't appear to need the additional bandwidth or reduced latency. This may change in the future, but for now the move to AM2 and DDR2 memory looks like it will yield far too little in performance improvements to keep AMD competitive in the upcoming desktop marketplace.
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phial - Thursday, July 5, 2007 - link
"Comments are often made that any evaluation of AM2 should include overclocking. Those theorists argue that the faster processor clock will move AM2 to the higher "bus" speeds that make for better efficiencies of the DDR2 memory controller - or something along those lines."OK who hired this guy? He knows NOT what he speaks of. Its apparent through the entire review.
phial - Wednesday, July 4, 2007 - link
"This will likely shift to patterns similar to those seen in bandwidth positioning as the AM2 memory controller is further refined and game patches make better use of AM2 capabilities."Wow... and your posting hardware reviews on a high traffic website.. amazing...
Zebo - Tuesday, April 18, 2006 - link
I get everest of 42ns 2-2-2 @ 200 with FX60 speeds on DFI NF4. I get 36ns when cranking up to 250mhz 2-2-2. And that reminds me - I guess you did'nt want to embarres AMD's new chip too much by putting old, supported, DDR 550 @ 2-2-2 in there huh?What a dog this change is.
Wesley Fink - Wednesday, April 19, 2006 - link
Actually our Beta motherboard and CPU were not 100% stable at 275. Also I don't have any memory that will do DDR550 (275 clock speed) at 2-2-2. Perhaps you mean another speed or other timings.Our Crucial 2GB kit can do DDR500 at 3-2-3 timings, but our DDR2-800 memory is also capable of doing 3-2-3 at some speeds if the beta motherboard had supported those timings. That's the reason we compared 3-3-3 500, which should be very very close to each memory's top performance and a fair comparison.
Our latency testing was at a slower speed than your FX60, which is why you got lower latency numbers. We did, however, set both the DDR and DDR2 platforms to the exact same speed and ratios for all the benchmarking. The results comparison was as fair as we could make it.
spinportal - Tuesday, April 18, 2006 - link
Let's see.. the 1GB PC-4400 DDR-550 kit is roughly 200$US for 2.5-3-3 timing. The DDR2-667 PC-5300 1GB kit is ~180$US for 3-3-3 timing for use to OC to DDR2-833. Unless I'm missing something, I don't understand your beef about spending $20 more for equal performance and using more juice.puffpio - Monday, April 17, 2006 - link
I can see gaming benchmarks being VERY graphics and cpu calculation intensive...but in terms of the bus between the cpu and main memory..i dont see it as that intentive
I wonder if a multitasking benchmark w/ lots of datasets would show off the increased bandwidth? (giant spreadsheets, databases, image processing, video encoding, etc etc)
shady28 - Tuesday, April 18, 2006 - link
"Real world" single user and light multitasking apps aren't going to use up the bandwidth. A heavy duty multitasking environment is what's needed to really test the benefits of dual core + DDR2. The thing is, this doesn't really describe what most PCs spend 99% of their time doing.
That said, Conroe does look promising, and I'm interested to see what AMD can come up with to counter it. The initial performance advantages, according to *Intel* benchmarks, are pretty significant. Hopefully AM2 is just laying the groundwork for faster processors from AMD. Still, I can't help but think the performance boosts we've been getting since about 2001 (3.06Ghz P4 HT) are marginal, and that this is yet another marginal boost.
NullSubroutine - Monday, April 17, 2006 - link
I am still convinced that the transition from DDR to DDR2 is primiarily because it unifies the memory production industry, lowers power for server and mobile areans, increases memory bandwidth for upcoming memory hog (ie vista), and servers as a platform of increased memory capability. As for the last point I think most of us believe that quad core CPU's may use more memory bandwidth and the original DDR may act as a bottleneck for the system. I also think it is clear that memory bandwidth is not a bottleneck for AMD, but I applaud them taking care of a potential bottleneck before it exists, unlike Intel who has continuelly bottlenecked their CPUs by insuffient memory bandwidth.NullSubroutine - Monday, April 17, 2006 - link
should say serves obviously.
eRacer - Sunday, April 16, 2006 - link
Was the DDR2 using a 2T command rate and was the DDR-400 tested using 1T? Is there an option to change the command rate on the AM2 motherboards? I believe at least some Pentium DDR2 motherboards with NVIDIA chipsets have the option to use a 1T command rate.I've seen some Sandra 2005 standard memory tests gain 500MB/s or more just by using 1T instead of 2T. A gain like that would allow DDR2-533 1T to score higher than DDR2-800 2T in the Sandra 2005 standard memory test. If DDR2-800 could use a 1T command rate the performance gain in the non-synthetic benchmarks might be a few percent higher on average. While that doesn't sound like much it would be roughly double the DDR2-800 performance advantage over DDR-400 in this review.