Stock Memory Performance

Most of today's motherboards that support DDR2 provide a wide range of memory ratios that match available DDR2 memory. End-users can select the memory ratio that matches their DDR2 memory speed. Our memory testing uses the same approach. We first test all of the stock ratios at the fastest stable timings we can achieve at the given ratio. With ratios, CPU speed remains the same at 2.93GHz in our memory test bed, and memory speed is varied by selecting different ratios.

The memory controller for Intel Socket T (Socket 775) motherboards is in the chipset, instead of part of the processor as in AM2 systems. Therefore, there is the potential for some memory performance anomalies. There is theoretically a small performance penalty for speeds other than a 1:1 ratio (DDR2-533 in this case) on boards designed for Intel processors. However, the actual performance penalty has been found to be very small with minimal impact on test results. As a result memory scales nicely through the various speed options.

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DDR2 memory is then pushed from the highest stock ratio that could be achieved in testing - in this case 1067 - to the highest FSB speed at the stock multiplier. A fortunate accident occurred in test results for the OCZ Flex XLC in that the highest stable memory speed on the P5W-DH of 1172 represents a base CPU speed of 293. By lowering the multiplier to 10 we were able to keep the overclocked memory test results at the same 2.93GHz processor speed. This allows easy comparison of test results at a very high memory speed at the same 2.93GHz. Results for the standard multiplier of 11 are also included at the bottom of the table. These are the results that should be compared to past DDR2 memory test results.

No matter how you slice it, the simple fact is that the OCZ Flex XLC, tested on air cooling, is the fastest DDR2 memory tested so far at AnandTech. DDR2-1172 exceeds the rated speed of DDR2-1150 on one of the most demanding boards available for testing DDR2 memory. To put this in perspective, the previous overclocking champion on this test bed reached DDR2-1116. Flex XLC, at DDR2-1172 is more than 5% faster than the previous best. With these results it was time to see where this memory could go on the new NVIDIA nForce 680i chipset - a chipset that had exhibited some stellar overclocks in our initial chipset launch review.

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On the nForce 680i the OCZ Flex XLC took DDR2 memory performance to a new gold standard. On Air Cooling, Flex XLC reached DDR2-1300 at the rated timings of 5-5-5-18. This is 150MHz above the aggressively rated speed of DDR2-1150 (PC2-9200). The DDR2-1300 speed would be rated at PC2-10400, making Flex XLC the first DDR2 memory to break PC2-10000 in our memory testing.

Memory Test Configuration Memory Bandwidth Scaling
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  • photoguy99 - Saturday, December 9, 2006 - link

    Thanks for your help Wesley, it's just takes a little time for me to get my head around this stuff.

    Just to clarify, I think I see the answer two #2:

    If you have an unlocked CPU, the only benefit to this memory is a 5-8% performance increase.

    In this case I don't think it matters if you are an extreme overclocker - extreme as you wanna be - this is the only benefit you can ever get with this RAM with an unlocked CPU, no matter what you do.

    If you have the cash, nothing wrong with a small performance bump for $300 extra - I am not judging anyone who buys this, just trying to clarify.

    regards,
    pg

    Reply
  • photoguy99 - Saturday, December 9, 2006 - link

    apologize for double post, accident... Reply
  • photoguy99 - Saturday, December 9, 2006 - link

    Sorry for being ignorant here, but can someone help break this down:

    1) What % faster is FlexXLC-1150 on real life benchmarks (on average), compared to value DDR2-800, at the same CPU speed?

    2) Do I understand correctly that if you have an unlocked CPU multiplier, then the only benefit to this memory ever is the % improvement from question 1?
    Reply
  • Wesley Fink - Saturday, December 9, 2006 - link

    The tables on page 4 show performance at the same 2.93GHz from DDR2-400 to DDR2-1172. There are also results on the last line for the top speed on the 975X at stock 11X multiplier - so results can be compared to previous test results. You can see the performance differences in each benchmark in those tables. Performance increases are there as speed increases, but they are extremely small. We also commented several times in the review that those shopping for value per dollar should buy a good value to mid DDR2 memory rated at least DDR2-800.

    Flex XLC is for extreme overclockers who want as few limits as possible on their overclcoking. With the ability to run to DDR2-1300 it allows great flexibility in OC settings.
    Reply
  • photoguy99 - Saturday, December 9, 2006 - link

    Thanks for your help Wesley, it's just takes a little time for me to get my head around this stuff.

    Just to clarify, I think I see the answer two #2:

    If you have an unlocked CPU, the only benefit to this memory is a 5-8% performance increase.

    In this case I don't think it matters if you are an extreme overclocker - extreme as you wanna be - this is the only benefit you can ever get with this RAM with an unlocked CPU, no matter what you do.

    If you have the cash, nothing wrong with a small performance bump for $300 extra - I am not judging anyone who buys this, just trying to clarify.

    regards,
    pg

    Reply
  • cmdrdredd - Friday, December 8, 2006 - link

    Why is there no 1T memory results testing? The bandwidth scores from this memory even at DDR2-1300 are pathetic to say the least. My Current system with 2Gb crucial DDR2-667 10th anniversary running DDR2-1000 at 5-4-4-8 gets 7607 Int/7631 Float buffered scores with Sandra. This is on a P5B Deluxe with E6400 running 3.2Ghz (400x8) Reply
  • Wesley Fink - Saturday, December 9, 2006 - link

    We try to get memory as close to stock speed and multipliers as possible in our testing, which yields comparable data but not the higher bandwidths you are seeing at extremely high bus speed overclocks. End users can get high numbers with overclocking, which are great for ego comments, but that tell us very little about comparative performance. Run your memory at the same settings and compare bandwidth. Those are numbers that relate to memory comparisons. This memory will run at 8x400 just like you are using and bandwidth will be similar to what you are seeing.

    The standard bandwidth scores at DDR2-1300 are pretty much in line with expectations, but the unbuffered scores are extremely low. We don't yet have an answer for why that is the case on the 680i but we are trying to find answers. The 680i runs a 2:3 ratio at that speed, where the 975X is running 1:2 at its highest speed. The underlying "strap" can make a huge difference in apparent memory performance and it is usually programmed by the board maker, and not always visible or adjustable to the end user.

    1T is useful for a very small performance increase on some boards, generally below DDR2-800. However, that option is not available on all boards and it really makes a small differenc on current DDR2 platforms. The differences you are seeing in bandwidth are the result of high FSB overclocks and not 1T.
    Reply
  • Hulk - Friday, December 8, 2006 - link

    I for one feel the most important part of a memory review is what timings will it run at each frequency and at what voltage?

    I realize that info is in the memory reviews but always in a little table that you must click to enlarge.

    Please put the timings/speed/voltage in a bar graph as well. Speed on the x-axis. Timings and voltage in the horizontal bar for each speed tested. We know that if the memory works at a certain frequency/latency/voltage the performance will be the same for any stick at those conditions.

    Better yet, tell me how fast it will run 4-4-4-12 and 5-5-5-18, as well as a few other timings.

    But as always the reviews are great. Thanks for your hard word.
    Reply
  • yyrkoon - Friday, December 8, 2006 - link

    I'm curious, if the savvy enthusiast used chilled air in place of water, what the end results would be. I don't think it would be hard to built something that forced cool air through these memory sticks instead of water. i.e. Chilled air in, and hot air vented out.

    End result should be a cooler safer system overall.
    Reply
  • Griswold - Saturday, December 9, 2006 - link

    Other than "for shits and giggles" I see no point in doing that. Water will do a better job. Remember, air is such a bad heat conductor, compared to water.

    A properly installed watercooling system is also very safe.
    Reply

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