IntroductionCorsair 1GByte DDR2 Twin2X Matched Memory Pair
Intel decided this it was time to modernise the major facets of motherboard architecture this year. To that end, it launched 900-series chipsets that took advantage of new-fangled PCI Express, more robust SATA implementation, and the use of DDR2 system memory. Each of these changes were viewed as Intel's efforts to eliminate potential motherboard-related bottlenecks arising from present traditional board design.
DDR1's days were numbered when both major players moved on to using DDR400 memory for their performance chipsets. Empirical evidence from the graphics card market, which is always a few steps ahead of motherboards when it comes to using high-speed memory, showed that DDR1's usefulness extended to no more than DDR500 levels. After that, DDR2 took over, and now GDDR3 is used to provide RAM speeds in excess of DDR1000. Intel's decision to ditch DDR1 came at just about the right time. It will soon be validating memory controllers that require DDR533 and even DDR600 modules for synchronous CPU operation. Sure, Corsair and OCZ, amongst others, produces ultra-fast DDR1 RAM, but at the cost of additional voltage and considerable expense.
So we know that DDR2 is able to run at frequencies much higher than DDR1. That's good news for Intel, but the mechanics behind DDR2 are often misunderstood. I'll point you in the direction of Ryszard's DDR2 summary. Put simply, DDR2's data buffers run double the speed of DDR1's, such that core DRAM frequency needs only to be half that of DDR1's. It's like using 4 arms instead of 2, if you will.
Other than a simple doubling of data buffer speeds, DDR2 also introduces on-die termination (allows for excellent signal quality), a different layout (240 pins vs DDR1's 184), and lower operating voltages (1.8v vs. 2.5v). The downside, however, is in accepting higher access latencies (read lower performance for a given core speed), lack of backward compatibility and cost, inevitably.
Intel reckons the benefits outweigh the disadvantages. This may hold true over the long term when, say, DDR800 speeds are required, but the current general consensus seems to be that Grantsdale and Alderwood chipsets' performance is being checked by inefficient DDR2 memory. It's kind of depressing when previous generation's boards, when paired with identical processors, outperform what is supposed to be cutting-edge technology.
Whatever the wrong and rights, DDR2 is here to stay. Compliant modules have been shipping for a few weeks now and Corsair were one of the first manufacturers to try its hand at DDR2. The above discussion is a lengthy, roundabout way of stating that our review item for today is Corsair's 1GByte DDR2 Twin2X Matched Memory Pair set.