Feature Articles

Evolution of Memory Performance: A DDR3 Story

By Zachary Chan - 26 Jun 2007

Overclocking DDR3

Overclocking DDR3

We will also be running a few overclocking tests to ascertain the benefits of both improved bandwidth and improved latency towards DDR3 performance. Bandwidth overclocking is a pretty straightforward affair to see how well DDR3 performance scale with speed increase. We initially wanted to benchmark at DDR3-1600 timed at 9-9-9-25. However, our HyperX modules could not be overclocked that high. In the end, we had to settle for DDR3-1500 at 9-9-9-25. At these speeds, motherboard FSB will have to be boosted to 1500MHz (375MHz base) and the processor running at 3GHz (375x8).

DDR3-1333 memory overclocked to DDR3-1500.

For latency tests, we reduce DDR3-1333 timings from 9-9-9-25 to 7-7-7-20, similar to the DDR3-1066 SPD latencies. From our benchmarks before, you can tell that DDR3-1066 doesn't really provide much improvement over DDR2. Once we move towards 1333MHz processors and higher speed DDR3-1333, memory latencies will increase even further, which counters potential performance improvements from the speed bump. So, how will DDR3-1333 perform if it could operate with the same latencies as DDR3-1066? Check out the results below and see for yourself.

DDR3-1333 memory running at a lower CL7 timing than its usual SPD of CL9.

Under normal situations, our pair of Kingston HyperX DDR3 memory could run at 1.5V up to DDR3-1066. At DDR3-1333, we found that the memory worked fine at 1.7V (Kingston's recommended voltage for this speed). Then at DDR3-1500, we had to jack up the voltage again to 1.95V. Heat was not much of an issue till you pass the 1.8V mark where the memory stick becomes apparently hotter even when idling. As we had to overclock the whole system in order to benchmark different memory timings, the following table is a quick cross reference of actual frequencies and timings used in the benchmarks below.

DDR3 Timing Comparison Table
  DDR3-1066 DDR3-1333 DDR3-1500
FSB 1066MHz 1333MHz 1500MHz
CPU 2.93GHz (266x11) 2.997GHz (333x9) 3.0GHz (375x8)
Timing 7-7-7-20 9-9-9-25 (normal) / 7-7-7-20 (OC) 9-9-9-25
Voltage 1.55V 1.70V 1.95V

Under a synthetic benchmark, there was a visible performance improvement when overclocked up to 1500MHz. DDR3-1333 at CL7 also showed a marked improvement over CL9, putting it almost on par with DDR3-1500 as well. In real world application benchmarks though, we were able to see improvements from DDR3-1066, but there wasn't much of a significant increase even after overclocking.

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