DDR2/DDR3 Overlap Speeds - OCZ Introduces DDR3-1800
In Kingston Launches Low-Latency DDR3, memory performance was compared at the DDR2 and DDR3 overlap speeds of 800 and 1066 MHz. With the retesting of memory in the new test bed it was worthwhile to compare memory, at least in this initial review, at the overlap speeds. This presents the opportunity of seeing how top DDR3 performance compares to the DDR2 performance with which you are familiar.
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At 800 MHz, DDR2 is capable of 3-3-3 timings, while DDR3 is limited to CAS 5 in the ASUS P5K3 Deluxe BIOS. With that severe timing limitation, which is the result of the much higher speeds available with DDR3, the DDR2 memory is generally the fastest solution. The latest Elpida (Kingston) and Micron Z9 (OCZ) chips still beat the last generation DDR2 in the Intel P965 motherboard in almost every case. However, the latest P35 Intel chipset driving DDR2 instead of DDR3 is still the best performer at 800 MHz - simply due to the advantage of CAS 3 compared to CAS 5 timings.
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At the overlap speed of 1066 DDR2 still enjoys a timings advantage over DDR3 on the ASUS board. The fastest DDR3 CAS timings of 5 limits the best DDR3 timings to 5-4-3 compared to DDR2 at 4-4-3 with Corsair Dominator DDR2. Even with the timings advantage, DDR2 is only truly the better performer when running on the P35 chipset. The advantage for DDR2 here is very small to non-existent, however, as DDR3 results top a couple of the P35 DDR2-1066 benchmarks and the Elpida and Micron Z9 generally outperform DDR2/P965 across the board.
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By 1333 the timing advantage for DDR2 is gone and DDR3 pulls clearly in the lead in all benchmarks. The Micron Z9-based memories top the 1333 performance charts in all benchmarks, and this is just the beginning of a range that extends to DDR3-2000 and beyond for some of these memories. Keep in mind that memory in these three charts are all running at the same 2.66GHz CPU speed, and that only the memory speed has been changed by varying ratios. It should be obvious in these results why Intel elected to move to the 1333 bus and the faster speeds of DDR3 memory.
Going up from DDR3-1333 to DDR3-1600, DDR3-2000 and beyond further extends the performance lead for DDR3 as you will see in the next three pages of DDR3 performance results on the same benchmarks. With the change to the 3.0GHz processor speed to allow memory tests through DDR3-2000 at the same CPU speed, all benchmarks were rerun at the 3.0GHz CPU speed with 800, 1066, and 1333 memory speeds. This allows a linear comparison of DDR3 memory at all available memory speeds while the CPU speed remains at a constant 3.0GHz.
For this and subsequent DDR3 reviews, DDR3 performance will be compared at 800, 1066, 1333, 1600, 2000, and the highest memory speed for the tested memory. 1000 is the logical base for the 333 strap, as is 1666, but current ratios limit realistic benchmarking to the 1066 and 1600 reference speeds. We will change to the 1000 and 1666 speed options as soon as available memory ratios in the BIOS allow a more convenient means to select 1000 and 1666 as memory speeds at a consistent processor speed. Those ratios are not currently available in the ASUS P5K3 Deluxe BIOS - or in any other DDR3 compatible motherboards at present.
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