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Overclocking

Since we have already discussed the performance of high-speed overclocker memory kits in our previous article called PC2-9200 and PC2-10000 SDRAM: Ultra High-Speed Memory from Corsair and OCZ, we are going to focus mostly on the overclocking potential of the OCZ DDR2 PC2-9200 Reaper HPC Edition memory kit this time.

For our overclocking experiments I put together a testbed with an overclocked Intel Core 2 Extreme processor and eVGA 122-CK-NF67-A1 mainboard (Designed by Nvidia) based on the most suitable for DDR2 SDRAM overclocking Nvidia nForce 680i SLI core logic set. So, our test platform looked as follows:

  • Intel Core 2 Extreme X6800 CPU working at 3.2GHz (8 x 400MHz);
  • eVGA 122-CK-NF67-A1 mainboard (LGA775, NVIDIA nForce 680i SLI);
  • PowerColor X1900 XTX 512MB graphics card (PCI-E x16);
  • Western Digital WD1500AHFD HDD (SATA150);
  • Microsoft Windows Vista x86 OS.

Since Nvidia nForce 680i SLI chipset allows pseudo-synchronous memory clocking, the FSB frequency remained unchanged during our memory overclocking experiments. To ensure the system was running stably during DDR2 SDRAM overclocking, we used Memtest86, S&M and SP2004/ORTHOS utilities.

First of all I decided to find the maximum frequencies for the most widely spread timing sets when the memory modules can work stably and reliably. The DDR2 SDRAM memory kits were tested at their nominal voltage of 2.3V. The tests were run with Command Rate set to 2T and then to 1T. Note that only Nvidia chipsets from nForce 600i series and AMD/ATI RD600 chipsets for Intel Core 2 platform allow using 1T Command Rate setting.

So, you can see the maximum frequencies for each set of timings on the chart below. These are the frequencies when the memory remained stable and reliable.

Overclocking potential of OCZ DDR2 PC2-9200 Reaper HPC Edition with 2T Command Rate appeared quite to our expectations. We have seen very similar results when we tested a similar kit from the OCZ FlexXLC series. Here I can just repeat what we have said before, mainly, that the memory modules have not very high frequency reserve above the nominal speed. Besides, these modules cannot please us with any phenomenal ability to work at aggressive memory timings.

Here I would like to add that unfortunately, the increase of the memory voltage to the allowed 2.35V doesn’t help us better overclock OCZ DDR2 PC2-9200 Reaper HPC Edition kit with 5-5-5-15-2T timings.

Now let’s check out the benchmark results with 1T Command Rate setting.

The difference between OCZ DDR2 PC2-9200 Reaper HPC Edition and OCZ DDR2 PC2-9200 FlexXLC Edition is evident. The Reaper memory kit overclocks a little worse than its counterpart, however it still manages to hit 800MHz frequency with 4-4-4-12-1T timings.

In the meanwhile I would also like to share with you minimal timing settings with which our today’s hero can operate at different typical frequencies:

Memory frequency

Minimal timings

1150 MHz

5-5-5-15-2T

1067 MHz

5-5-4-14-2T

800 MHz

3-4-3-10-2T or 4-4-3-11-1T

In conclusion I wanted to compare the efficiency of the cooling systems used for different memory modules these days. Especially since we a few representatives of different interesting families at our disposal: Corsair Dominator, OCZ FlexXLC and OCZ Reaper HPC, designed to run at equal default frequencies of 1150MHz. To compare the efficiency of the cooling systems in question we measured the temperatures of the memory heat-spreaders after 30 minutes of running SP2004/ORTHOS test. All memory modules worked at their default timings of 5-5-5-15, with the same 2.3V voltage and 1142MHz frequency. We didn’t use liquid-cooling for OCZ FlexXLC and Dominator AirFlow Fan for Corsair Dominator. Here are the results:

Temperature (Burn)

Corsair Dominator TWIN2X2048-9136C5D

50°C

OCZ DDR2 PC2-9200 FlexXLC Edition

49°C

OCZ DDR2 PC2-9200 Reaper HPC Edition

52°C

Our practical tests show that the best thermal mode for the memory is provided by FlexXLC heat-spreaders from OCZ. The use of copper parts and relatively large heat dissipating surface size do their job very well. As for the Reaper HPC cooling system, these heat-spreaders with heatpipe technology proved to be lest efficient of all. They fell 3°C behind the leader.

 
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