by Ilya Gavrichenkov
05/11/2007 | 11:21 AM
If you have read our recent article devoted to high-speed memory kits called PC2-9200 and PC2-10000 SDRAM: Ultra High-Speed Memory from Corsair and OCZ you probably understood already that the manufacturers resort to two major means for reaching ultimate speeds: increase of the memory voltage and use of advanced cooling solutions. And if the first one is quite clear without any additional explanations, this is a very simple and straight-forward measure, then the technologies intended to improve heat dissipation from the memory chips give the developers some room for imagination.
For example, Corsair engineers suggest installing four heat-spreaders per memory module (according to their Dual Heat Exchange technology), while their colleagues from OCZ designed their own liquid-cooling system called Xtreme Liquid Convention that allows including the memory subsystem into the liquid-cooling structure. Unfortunately, we didn’t manage to pay due attention too all available cooling solutions for high-speed DDR2 DIMMs available these days. Another memory kit with something completely new onboard arrived into our lab a little later, so we decided to devote a separate article to it.
Today we are going to introduce to you another OCZ product belonging to the new Reaper HPC series – overclocker memory kit using heatpipe cooling system for proper heat dissipation.
Although OCZ Reaper HPC line-up cannot boast the same ultimate frequencies as Corsair Dominator and OCZ FlexXLC families, it boasts one very important competitive advantage: lower price. As a result, OCZ Reaper HPC memory modules are currently one of the best high-speed memory solutions from the price prospective, which definitely attracts numerous enthusiasts’ attention.
In our today’s article we will investigate the potential of the top kit from OCZ Reaper HPC family intended to run at 1150MHz and will compare its practical characteristics against those of similar solutions from OCZ FlexXLC and Corsair Dominator families.
From the formal specifications standpoint, OCZ DDR2 PC2-9200 Reaper HPC Edition memory kit is very similar to other solutions designed to work at 1150MHz default speed. It includes two memory modules, 1GB each, that can and should be used in dual-channel mode, according to the manufacturer’s initial intention. They boast 2.3V nominal voltage. At this voltage setting they are claimed to work with 5-5-5-15 timings at 2T Command Rate, according to the official specification. In other words, the official specs of OCZ DDR2 PC2-9200 Reaper HPC Edition are exactly the same as those of the recently reviewed OCZ DDR2 PC2-9200 FlexXLC Edition. And they boast exactly the same manufacturer guarantees regarding the ability of these modules to work stably with the voltage increased to 2.35V during overclocking.
In other words, the cooling system with heatpipes is the only distinguishing feature about OCZ DDR2 PC2-9200 Reaper HPC Edition that immediately catches your eye. Its design is not so sophisticated. The module PCB with memory chips is covered on both sides with black-anodized aluminum plates with nit very deep ribbing. These plates are closing in above the PCB pressing against a copper heatpipe going through a special groove. This heatpipes transfers heat from the upper side of the plates to the additional aluminum heatsink located right above the module. The heatsink is pretty small, with cross-shaped cross-section and is threaded onto the upper part of the heatpipe.
All in all, this cooling system looks very impressive, so far no one has used heatpipe technology for memory modules cooling. However, if you think about it, then OCZ Reaper HPC concept may seem not very reasonable from the practical standpoint. In this case the heatpipe you see will look more like a popular overclocking accessory of this season that should be present on any overclocker-related product. It is true, that heatpipes are usually used if the heated element cannot for some reason be equipped with a heatsink of adequate size. Thanks to their features, heatpipes allow to increase the distance between the cooled element and the heatsink that acts as primary heat-dissipating surface.
In case of OCZ Reaper HPC it is hardly that necessary to transfer the heat to a relatively small heatsink with not very large heat dissipation surface area. They could have achieved the same cooling effect by providing the plates on both sides of the DIMM PCB with deeper ribs or by making these plates taller.
The heatpipe that is used in the modules design is not just unnecessary: it also increases the height of the memory modules making OCZ DDR2 PC2-9200 Reaper HPC Edition 66mm tall. The use of heatpipe technology for OCZ Reaper HPC modules could only be justified if the heatsink above the memory subsystem were larger than the standard memory module dimensions. However, it is not the case here.
So, the copper heatpipe of the modules we are discussing today is more of a decorative element, which goes very well with the black aluminum plates and heatsinks. The stylish finishing touch to the exterior looks of OCZ DDR2 PC2-9200 Reaper HPC Edition is the company logo on one side of the module and the white sticker on the other. By the way, this sticker carries information on the product part number, speed, timing and capacity.
The memory modules SPD contain the data ensuring the kit’s compatibility with all mainboards. The actual specifications should be stored in the EPP. The profile does contain the correct timings, however, the working voltage is 0.2V lower. As for the working frequency, I have to complain once again about the Everest utility that doesn’t provide the correct reading.
Summing up a few things I have to say that if we disregard the cooling system of the OCZ DDR2 PC2-9200 Reaper HPC Edition for a while, then they will be close relatives to OCZ DDR2 PC2-9200 FlexXLC Edition. Both products are built using the same Micron D9GMH (B6-3) chips that are actually used for the majority of high-frequency DDR2 SDRAM memory modules for advanced users out there.
OCZ DDR2 PC2-9200 Reaper HPC Edition
2 x 1GB modules
Micron D9GMH (B6-3)
Reaper HPC cooling system
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:
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:
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:
Corsair Dominator TWIN2X2048-9136C5D
OCZ DDR2 PC2-9200 FlexXLC Edition
OCZ DDR2 PC2-9200 Reaper HPC Edition
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.
The OCZ DDR2 PC2-9200 Reaper HPC Edition memory kit we have reviewed today didn’t surprise us with anything. It is very similar to OCZ DDR2 PC2-9200 FlexXLC Edition in technical specifications as well as in practical performance. I would only like to draw your attention to slight lag of the overclocking potential with 1T Command Rate that can be explained by less efficient cooling solution than FlexXLC. The use of heatpipe technology in Reaper HPC system doesn’t have that much of the cooling effect and plays more of a marketing or designer role.
However, considering that OCZ DDR2 PC2-9200 Reaper HPC Edition memory modules are much cheaper than OCZ DDR2 PC2-9200 FlexXLC Edition, they are very likely to find a lot of fans.