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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  • yyrkoon - Saturday, December 9, 2006 - link

    There is no "for shits and giggles" about it, it would help. How much it would actually help would be open for debate (until someone actually tested it).

    For one, it would help, because, IF you for example had air coming in from the bottom, and air exiting out through the top, you would be using convection to recycle cooler air from the outside, and the heat would travel out through the top. To some small degree, you wouldn't even need a pump to accomplish this. This would also keep hot air from recycling, well, at least concerning *from* the memory(to a small degree) , which wouldn't mean a whole lot.

    Now, if instead of using convection, you use forced air, whether chilled or not, dependent on the CFM pushed through, you *could* reduce the temperature on the heat spreaders drastically. This may not cool as well as water, but there would be no chance of water leakage either, and would result in a definite improvement. Granted, I can not see people wanting to go out an buy a <insert brand here> air compressor, for what whatever amount, when it would be cheaper to go water(which, its self, isn't cheap either). I've priced components for a good water cooling system, and we're talking around $400 usd, for a decent setup, which IMO, would be better just spending the extra cash on a better/faster CPU(if possible). Less problems, and hassle.

    Never seen a Dell that uses a plastic "funnel" over the CPU, without a CPU fan directly over the CPU? They exist, and they do very well in keeping the system very cool. Same concept, on a smaller scale.
  • Larso - Monday, December 11, 2006 - link

    Though the idea is interesting, I think you would be better off pushing air over the cooling fins the usual way, than to push air through the water cooling intake. Remember that air and water have very different properties and the cooling interfaces has been designed to optimize each of those elements.

    It could be an interesting experiment I must admit, but I suspect you would get just get a lot of hissing noise from the end of the hose - and not a lot of cooling...
  • cruzer - Saturday, December 9, 2006 - link

    If you pumped cold air in through the block, you will get condensation in the lines. Reply
  • PrinceGaz - Saturday, December 9, 2006 - link

    Erm, no you wouldn't. Condensation only forms when the air is cooled down by something, such as on a cold window in a warm room, because cooler air is unable to hold as much moisture as warm air so excess moisture has to be dumped as condensation when the relative humidity reaches 100%.

    Pumping cold air through the block carries no risk of condensation because the air will be warmed rather than cooled. In fact it would be an effective way of removing any moisture because the air warmed by the block would have a fairly low relative humidity.
  • yyrkoon - Friday, December 8, 2006 - link

    Hell, I'd even venture to say that if you forced room temperature air through these fast enough, even on a warm day, the results would be great. Granted, you would have to be strategic about it. Reply
  • Frumious1 - Friday, December 8, 2006 - link

    I realize you don't normally test water cooling (or cooling products in general), but it seems one of the major points for this RAM is that it is ready to be used with water cooling. Rather than speculating about if it will help or not, how about actually testing it? Seems like this RAM would be great for people looking to build a silent system, as you now don't have to worry about the RAM overheating either with water cooling.

    Also, this wasn't mentioned in the article, but can you fit two DIMMs next to each other? Meaning, could you go all the way to four DIMMs? Reason I ask is that if you can't then there are going to be some boards where this RAM won't work at all in dual channel mode. Hopefully OCZ wasn't so shortsighted as to make the DIMMs take more than a single slot width, but at the same time I don't know how you get effective water cooling without the HSF getting quite a bit thicker than the typical heatspreader.
  • Wesley Fink - Friday, December 8, 2006 - link

    We should have mentioned that the OCZ Flex XLC is thin enough that 4 dimms can be fitted in standard memory slots. We tried side by side slots in a number of boards and the dimms fit fine side-by-side.

    We considered testing with water also, but we did not have the correct fittings available, it would have taken a while to get the fittings we needed, and we wanted to get the info to our readers as fast as possible. OCZ emphasizes the Flex nature of the memory, and we thought you would want to know about the outstanding performance on air with Flex XLC.

    Perhaps we will relent and test with water in a future review, but we're not completely sure we want to go in that direction. We generally find we can overclock using air cooling at speeds similar to some other sites who insist you can only cool with water.

    The "silent" aspect is a good argument for water cooling, but most water systems still have a fan to cool the liquid and a pump for recirculating the fluid. Some water cooling systems are therefore about as "noisy" as a good air-cooled system - though we do agree that many water cooling systems are very quiet.

  • brownba - Friday, December 8, 2006 - link

    no doubt the water cooled feature should have been tested.

    I'm also wondering how the heatsink is designed - does the water flow down the front of the stick over the actual memory chips?
  • Hypernova - Friday, December 8, 2006 - link

    If you look at the last page on the "Pre-CES Taiwan 2006, Day 1" article that's exactly what they had in there. Reply

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