Memory Configuration (continued)

Our benchmarks in Part 1 were consistent with the configuration recommendations in the Intel White Papers for Memory Configuration of the 875 and 865 chipsets. We concluded with the following performance charts based on our testing and the information provided by Intel. We differ from the Intel White Paper charts only in the first and second positions for the Intel 865 chipset. When Intel published their White Papers, we doubt that they had any notion that most of the 865 motherboards being sold would have some version of PAT (Performance Acceleration Technology) on board. Our testing of the ASUS, AOpen, and DFI PAT-enabled boards shows that the PAT 865 boards behave more like 875 boards. We have confirmed that the first and second positions on PAT-enabled 865 boards are, as we report, below — with four DS DIMMs performing faster than two DS DIMMs.

DDR400 (1:1) Performance DIMM Configuration Single-Channel or Dual-Channel
1 4 DS Dual Channel
2 2 DS or 4 SS Dual Channel
3 2 SS Dual Channel
4 4 SS/DS
Mixed Matched Pairs
Dual Channel
5 Any DS Single Channel
6 Any SS Single Channel

DDR333/266 Performance DIMM Configuration Single-Channel or Dual-Channel
1 2 DS or 4 SS Dual Channel
2 2 SS Dual Channel
3 4 DS Dual Channel
4 4 SS/DS
Mixed Matched Pairs
Dual Channel
5 Any 1 or 2 DS or SS
(1 DIMM or 1 in each Channel)
Single Channel
6 Any 1 SS Single Channel

While SiSoft Sandra UNBuffered Memory Test results demonstrated real differences in performance among these memory configurations, many of you asked what we might see in real-world performance differences with these different memory configurations.

Some of the configurations were easier to test than others. Kingston had provided us with four Single-Bank (single-sided) DDR500 DIMMs that allowed us to look at performance differences in two SS DIMMs versus four SS DIMMs. We looked at performance of 1000FSB/DDR500 at 3-4-4-7-1 memory timings at 2.65V.

1000FSB (3.0GHz)/DDR500 Performance — Kingston PC4000
2 x 256 MB SS DIMMs vs. 4 x 256 MB SS DIMMs
Number of Single-Bank DIMMs Quake3
Sandra UNBuffered Sandra Standard
Super PI 2M places
(time in sec)
2 386.30 INT 2821
FLT 2786
INT 5830
FLT 5748
4 394.57 INT 3218
FLT 3195
INT 5841
FLT 5818

While the differences in Quake3 frame rate and Super PI times are small, keep in mind that the only change here is using four SS DIMMs instead of two SS DIMMs. As predicted by Sandra UNBuffered Memory Test, the four SS DIMMs perform better than two SS DIMMs.

Comparing two SS DIMMs to two DS DIMMs was done using 2 x 256 MB SS OCZ PC4000 and 2 x 512 MB DS PC4000 at timings of 2.5-3-4-6 at 2.65V. It is almost impossible to keep DIMM capacity the same, which would be the most accurate test, as none of the samples using the same memory chips would have the same exact capacity in SS and DS configurations.

1000FSB (3.0GHz)/DDR500 Performance — OCZ PC4000
2 x 256 MB SS DIMMs vs. 2 x 512 MB DS DIMMs
Number of DIMMs & Configuration Quake3
Sandra UNBuffered Sandra Standard
Super PI
2M places
(time in sec)
2 SS 392.30 INT 2918
FLT 2926
INT 5761
FLT 5868
2 DS 400.10 INT 3282
FLT 3324
INT 5965
FLT 5934

Again, the differences are small but real in Quake3 and Super PI, but with 2 DS DIMMs performing better as we had demonstrated in Part 1 with the Sandra UNBuffered Memory Test.

The fastest configuration should be 4 Double-Bank DIMMs on the Intel 875 chipset motherboard. Our first efforts to test this configuration, with 4 x 256 DS OCZ 3700 GOLD modules did not show 4 DS DIMMs any faster than 2 DS DIMMs on the ASUS P4C800-E. This was a real puzzle considering that other predicted configurations were easily verified with Quake3, Super PI and other benchmarks. When we looked deeper, the problem became clear. In every configuration that we had tested with the ASUS P4C800-E, the Performance Mode showed “enabled” but with 4 DS DIMMs at any FSB speed faster than 800, CPU-Z 1.18C shows Performance Mode “disabled”. Our trial was failing here because we were comparing 2 DS DIMMs with PAT on to 4 DS DIMMs with PAT off. We have asked ASUS for the reason behind why PAT appears to be disabled at 4 DS DIMMs above 800FSB.

Since we were mainly concerned with comparing 2 DS with 4 DS DIMMs under the same conditions, we ran 2 DS vs. 4 DS tests at 800FSB/DDR400, so that PAT was enabled in both two and four DIMM setups. We compared prototypes of high-speed PC3700 memory that we tested, looking specifically at the performance of 2 x 512 MB DS to 4 x 512 MB DS at DDR400. Timings were 2-2-4-8 at 2.75V.

800FSB (2.4GHz)/DDR400 Performance
2 x 512 DS vs. 4 x 512 DS
Number of DS DIMMs Quake3
Flyby fps
Botmatch fps
Sandra UNBuffered Sandra Standard
Super PI 2M places (time in sec)
2 321.4 196.30 68.31 INT 2683
FLT 2722
INT 4704
FLT 4691
4 324.5 197.60 69.38 INT 2830
FLT 2923
INT 4678
FLT 4717

While the differences here are quite small, they still show 4 DS modules performing better than 2 DS modules. We suspect that we would see larger differences at higher speed, as we have in our other comparisons.

We have confirmed with game benchmarks and a number-crunching benchmark that the best 875/865 memory configurations can also be seen in real-world benchmarks. Because memory performance is only one component of game performance and overall system bandwidth, the effect on these benchmarks is, as expected, smaller than the variation seen in benchmarks that measure only memory performance, like Sandra UNBuffered Memory Test.

Does Memory Speed really matter in the Real World? The Candidates


View All Comments

  • dshodson - Friday, September 05, 2003 - link

    So what is the best memory to put in my new dell server coming in a week which has the 875 chip. I heard u cant really overclock this system although i havent received mine yet. Reply
  • Anonymous User - Tuesday, September 02, 2003 - link

    Sorry about the typos ( its 11:36 PM here )

  • Anonymous User - Tuesday, September 02, 2003 - link

    Uberclocker ,

    If your having a problem with a OCZ part , email me directly , Most problems are related it simple setup issues , and your problem is verry likely fixed in a few simple steps , or with a bios update

    My email is
    I will not like answer your email until tomorow ( tuesday ) as today is a holiday and I am not in the office today

  • Anonymous User - Monday, September 01, 2003 - link

    Hello, I have followd your recommendation and bought an OCZ 4000 in Germany, this weekend. Unfortunately it has not performed to its specification. Can you tell me if there is a special part number I should look for to get their special 'reviewers golden sample' ?

  • Anonymous User - Saturday, August 30, 2003 - link

    I think if you have a cpu that will do 250 FSB and you purchase memory based on this article and you get within 98% of the results posted in this article, you owe Wesley $10.00. If 20% of the people with favorable results donated, there would be no more need to advertise. Now for the people who did not purchase ram based on this article and are bitching about it being bias, what are you bitching for?. This article has not cost you a cent.

    Thanks Wesley, you saved me a $100 on ram. I almost got caught up in all the hype about 4000 and 4200.

  • Anonymous User - Saturday, August 30, 2003 - link

    This article goes part way to answering the question of what memory configuration is fastest but I was disappointed that there was no variation in ratio.

    I would like to see a review that tests agressive timings against high frequency to see what produces the best results.

    Also a test of all P4C chips running @ 3.6Ghz to see whether there's any benefit in buying the fastest chip.

    With most motherboards easily hitting 1Ghz are we likely to be seeing a P4D which supports a 1066Mhz FSB?
  • Anonymous User - Friday, August 29, 2003 - link

    I think the way to do these reviews is to tell the manufacturer you'd like to include them in a review, purchase the memory from a store you trust, and then get re-imbursed by the manufacturer. That way, there'd be no selected modules and you would know what you were going to put into the review (4 ss vs 2 ds).

    So, when do we get that part 2 of the 865/875 mobo roundup ?
  • retrospooty - Friday, August 29, 2003 - link


    I have run these tests myself on an IC7G at 200 , 230 250 and 280 FSB and found that 5:4 2-2-2 always beats 1:1 at 2.5-4-4, even 2.5 4-3 ... However SOME motherboards arent as efficient at 5:4 with some types of ram as others... If you try the same test on several different mobo's I think you will find that 5:4 2-2-2 is quite a bit faster in non-synthetic mem test benchmarks.

    Oldfart # 64, you are right about the reviewers and using the synthetic tests to boost sales. good point.
  • Anonymous User - Friday, August 29, 2003 - link

    If your not going to overclock, get low latency pc 3200 or 3500, the PC4000 wont help you at all

    even IF you ARE going to overclock, the PC4000 will not likely get you better performance.
  • Anonymous User - Friday, August 29, 2003 - link

    #67 I'm not an expert by any means but here is how I understand this discussion:
    If you are planning to use one of the faster processors such as the 3.0C you won't be able to achieve a big overclock because the multiplier for that processor is 15. If you want to use a higher speed processor such as the 2.8C or the 3.0c, you really dont need to spend the money on faster memory such as the PC4000 because you probably won't be able to overclock to a point that you will be able to reach a front side bus speed of 250mhz which is the lowest rated speed (x2=ddr500) of the memory module. So as the article has explained,you would be better off with
    slower ram that has faster timings. However, if you have a slower processor such as the 2.4C or the 2.6C, you should be able to achieve a higher overclock because these processors have lower multipliers. In this case you would need faster ram such as the PC4000, because with these processors many have been able to set their front side bus up to and beyond 250mhz. In most scenarios with fast processors/slower ram vs slower processors/faster ram, IMHO, the performance difference may be fairly equal. What is really happening is a cost/benefit consideration. As always be careful!!! Overclocking can damage your do it at your own risk!

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