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Summary

Somewhere between the ultra-high frequency and the ultra-low latency market is the moderate one size fits all PC3700 - PC4000 market, depending on whether the modules are specked conservatively or at the very edge of what they can actually deliver. In terms of overall performance and value some of these modules may not be a bad choice as we show in the review of the TwinMOS TwiSTER. . One caveat is that you get exactly what you pay for, no less but no more either.

The big question in this context is how much performance is being sacrificed or doesn't it matter at all?

Officially, the highest standard supported during the life span of DDR (or DDR-I to differentiate it from the upcoming DDR-II) is DDR400 also referred to as PC3200. PC3200 means a doubling of the original release speed of DDR 200 or PC1600 that was not even intended or projected at the original release of DDR. In retrospect, quite a few of the accomplishments we are taking for granted were subject to heated debates, the most prominent probably being the discussions about how far a TSOP design can be pushed and at which point there would be a mandatory transition towards a BGA connector type.

TwinMOS TwiSTER, click for larger image

In retrospect, some of the issues that were debated appear rather irrelevant, the entire question of whether it would even be possible to go beyond DDR333 is just one example for how much further DRAM technology has evolved. In insider circles DDR 400 or PC3200 is already considered entry level commodity speed grade, while the top grades are only starting at PC4400 or DDR500.

Naturally, the higher the frequencies, the higher will, in most cases be the access latencies, that is we are looking at a RAS-to-CAS Delay of 4 cycles, CAS latency of 3 cycles and Precharge delay of 4 cycles. Suffice it to say that in many streaming applications the higher latencies can be masked by the increased bandwidth, however, especially on any AMD platform, low latency still rules. Not only that, but it would also defy the purpose of the integrated memory controller of the Athlon64 that draws its strength from low decode latencies to add the latencies back in on the level of the memory itself.

Currently, the hot markets, therefore, are the ultra-low latency modules running at 2:3:2 or similar and, on the other end of the scale, anything that will run above 270 MHz. Keep in mind that, in the case of the latter, most of the time, the culprit is not the memory itself but rather the mainboard, unequal trace length and inadequate memory power circuitry are only two of the issues the memory has to fight in an up-hill battle.

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