DDR3 Round-Up: Core i7 Performance Analysis

Clock Speed

DDR3 is built to scale in terms of clock speeds. Initial speed grades of DDR3-800 and DDR3-1066 didn't show significant performance enhancements over DDR2 at the same clock speed. However, DDR2 has more or less been tapped out at a maximum clock speed of 1200 MHz. DDR3, on the other hand, has been able to quickly ramp up in clock speed, and now is available at speeds of 2000 MHz and higher with no end in sight.

We wanted to see how clock speed can affect system performance across the board. We configured a system with 6 GB of DDR3 and ran a set of sample benchmarks with the memory divider set to speeds of 800 MHz, 1066 MHz, 1333 MHz, 1600 MHz, and 1866 MHz, which appear to be the most common options on enthusiast class motherboards. As it's possible to set this divider without affecting any of the other system clocks, we can directly pinpoint how much performance is gained by additional memory clock speed alone. At each clock speed, memory timings were set to 9-9-9-24 for consistency across the board.

As you can see in the graphs above, there is a clear benefit to running higher-clocked memory. Performance increases as the memory clock increases, across the board.

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