by Ilya Gavrichenkov
09/13/2006 | 06:25 AM
After our checking the influence of memory subsystem parameters on performance of the Core 2 Duo platform in general, we now want to test a few DDR2 SDRAM kits that you can actually use in your system. Let's put theory to practical use, so to say.
Memory manufacturers are currently offering an abundance of products varying in the default frequency as well as timings. But besides the default mode specified by the manufacturer, the modules can be used in other modes as well. Memory that is meant to work at a high frequency can also do well at a relatively low frequency but with aggressive timings. So, judging different memory kits only by their specifications is basically wrong. Besides default characteristics, it is useful to know how memory performs in modes other than those declared by the manufacturer. That's exactly what we are going to do now - to check out some popular overclocker-friendly memory kits under non-standard conditions.
Right now, dual-channel DDR2 SDRAM kits consisting of two modules with a total capacity of 2GB seem to be the most interesting product. 1GB memory kits aren't a good choice anymore for top-end and midrange systems as we have stated in our earlier review. As for the memory frequency, modules rated for 800MHz and higher should be considered optimal for overclockers today.
In this review we'll focus on 2GB DDR2 SDRAM kits capable of working at a frequency of 1GHz and higher. We'll see what such kits are capable of in the Core 2 Duo platform that is winning more users with each day.
We used two mainboards for this test: an ASUS P5W DH Deluxe on the Intel 975X Express chipset and an ASUS P5B Deluxe on the Intel P965 Express. We had to use two mainboards because each has certain peculiarities when it comes to working with the memory subsystem. The BIOS Setup of the ASUS P5W DH Deluxe offers limited control over secondary memory timings, which affects an attempt to overclock DDR2 SDRAM above 1GHz. In other words, not all modules are capable of revealing their full potential on this mainboard when overclocked to frequencies of 1.0 to 1.1GHz. Users of this mainboard recommend sticking to the automatically assigned values for the memory subsystem settings, but we couldn't follow that advice in our overclocking tests. The other mainboard, ASUS P5B Deluxe, offers much more memory-related settings in its BIOS Setup, but is overall less stable than the ASUS P5W DH Deluxe when you choose aggressive memory timings.
To make sure the tested memory is stable in a particular mode, we used three utilities: Memtest86, S&M and Prime95. Quite a lot of popular performance benchmarks, even those that utilize memory heavily, run without problems under conditions that prove to be not stable if tested by special-purpose utilities. So, we use the mentioned three programs to be absolutely sure that the tested memory is stable at a given frequency and with particular timings.
We tested the memory modules at the voltage which is specified by their manufacturer as the default one.
A leading manufacturer of overclocker-friendly memory modules, Corsair offered us one of its top products, a pair of modules intended to be clocked at 1067MHz. Corsair has reached that speed ahead of all its competitors and TWIN2X2048-8500C5 is the only two-module memory kit in this review to be rated for a frequency above 1GHz.
The Corsair TWIN2X2048-8500C5 kit consists of two 1GB DDR2 SDRAM modules that are each marked as CM2X1024-8500C5. According to the manufacturer, the default operating mode for that kit is a frequency of 1067MHz with 5-5-5-12 timings. The default voltage is 2.2V.
Corsair TWIN2X2048-8500C5 modules are based on Micron's chips which are widely used by many manufacturers to produce overclocker-targeted DDR2 SDRAM. Such chips can overclock well after a voltage increase, which is confirmed by the fact that they can be overclocked above 1GHz by setting their voltage 20-25% above the value written in JEDEC's specifications.
To cool the overclocked modules, Corsair uses its traditional black-anodized aluminum heat-spreaders on both sides of each module. The manufacturer's logo is painted in white on the heat-spreaders, and the sticker tells you the part number as well as speed, timings and capacity of the product.
Corsair TWIN2X2048-8500C5 modules feature the so-called Enhanced Performance Profile (EPP) which was invented by Nvidia's engineering and marketing folks to extend the SPD information. The Profile contains more information about the memory module settings to be used in overclocked modes. So, you shouldn't be surprised at the impressive contents of the SPD chip:
As you can see, the Corsair TWIN2X2048-8500C5's SPD contains “safe” modes (DDR2-533 with 4-4-4-13 timings and DDR2-800 with 5-5-5-18 timings) that allow starting the mainboard up without any problems. To overclock and run the modules in their “default” mode you need to specify some settings in the BIOS Setup. It is to simplify this process that the EPP contains two overclocking profiles that allow to easily switch this memory into DDR2-800 mode with 4-4-4-12 timings or into DDR2-1066 mode with 5-5-5-15 timings. The EPP is currently supported only by Nvidia's 500 series chipsets, so you can't use the EPP info on Core 2 Duo platforms - you have to manually configure the memory subsystem through the BIOS Setup.
The test results of the Corsair TWIN2X2048-8500C5 kit are shown below:
As you can see, this memory kit can work at frequencies up to 1128MHz. At a frequency of 1GHz it allows using 4-4-4-12 timings.
GeIL didn’t send us a top product. The 2GB GX22GB8000DC kit is a rather inexpensive solution, but is claimed to be able to work at 1GHz, although with 5-5-5-15 timings and at an unusually high voltage of 2.3V. GeIL showed some bravery in declaring a very high voltage that is higher than the default voltage of most other memory modules overclocked to such frequencies.
The modules aren’t remarkable externally. The memory chips are covered with an ordinary stamped aluminum bar on both sides of the PCB. The heat-spreader carries a relief manufacturer’s logo and a sticker that tells you the part number, frequency, timings and voltage of the product.
GeIL claims they test their modules on i955X-based mainboards from ASUS, MSI, Abit and Gigabyte before selling them. We didn’t have any problems with ASUS’ i975X- and iP965-based mainboards, either. However, GeIL GX22GB8000DC modules do have different properties in comparison with modules on Micron chips. GeIL obviously have chosen some other chips for that product.
The modules’ SPD chip contains information that helps enhance their compatibility with mainboards.
DDR2-400, DDR2-533 and DDR2-667 modes are listed here, so you will have to configure the modules manually in the BIOS Setup to make them work at 1GHz.
GeIL cannot match the above-described modules from Corsair in practice, though.
After choosing 4-4-4-12 timings, the GeIL GX22GB8000DC cannot conquer the 1GHz frequency even though its default voltage is higher at 2.3V than that of the competing products. But when the less aggressive timings of 5-5-5-15 are selected, these modules prove to be usable not only at 1GHz but also at 1067MHz.
Like Corsair, OCZ Technology is a major trend-setter on the market of enthusiast targeted memory. The company offered an original product for us to test, which has few analogs among competing products. It is 1GHz memory with reduced latencies. OCZ DDR2 PC2-8000 Platinum Extreme Edition modules are capable of working at 1GHz with more aggressive timings than 5-5-5-15 which are customary for that frequency.
The kit consists of two 1GB DDR2 SDRAM modules that work at 2.2V voltage (which is in fact an unofficial standard for overclocker-friendly DDR2 SDRAM). The manufacturer claims the kit is capable of working at 1000MHz with 4-5-4-15 timings. Moreover, OCZ says the DDR2 PC2-8000 Platinum Extreme Edition kit can work at a higher voltage, up to 2.25V, without any risk of damage.
These modules can easily be identified by their looks. They have a very specific heat-spreader that you can only find on OCZ products as yet: meshed copper plates with platinum-color sputtering and a pressed-out letter Z in the middle.
The manufacturer describes these heat-spreaders with the abbreviation “XTC” which spells out as Extreme Thermal Convection. The meshed design indeed enlarges the surface area of the heat-spreader (besides giving it an impressive appearance), which eventually leads to better thermal conditions for the memory chips. The stickers on the heat-spreader tell you the part number, model name and default timings of the module.
The modules’ SPD contains information that complies with the specs: DDR2-1067 SDRAM with 4-5-4-15 timings.
Using chips from Micron, the OCZ DDR2 PC2-8000 Platinum Extreme Edition kit is very similar in characteristics to the competing products from other manufacturers, namely to the Corsair TWIN2X2048-8500C5 and to the Patriot PDC22G8000+XBLK.
The memory from OCZ can be clocked at frequencies above 1GHz at 4-4-4-12 timings. If the timings are relaxed to 5-5-5-15, it reaches a record-breaking frequency of 1145MHz. We guess this result could be improved upon by increasing the memory voltage.
Patriot’s PDC22G8000ELK modules are an offer for economical overclockers. Pricing them much lower than other DDR2 SDRAM modules intended to work at 1GHz, Patriot still managed to achieve quite acceptable characteristics. At their default 2.2V voltage these modules are expected to work at 1000MHz, although with “relaxed” 5-5-5-15 timings.
According to the manufacturer, the Patriot PDC22G8000ELK kit is meant for use with mainboards on i975X and i955X chipsets in the first place, but we had a number of stability issues trying to use it on our i975X-based ASUS P5W DH Deluxe mainboard. The memory was stable on our ASUS P5B Deluxe (with an iP965 chipset), though. So, Patriot PDC22G8000ELK modules is inexpensive but is not guaranteed to be stable on any mainboard you may want to use them with. This kit differs greatly from other memory modules in this review because it is based on chips from Elpida. On the other hand, Patriot guarantees that the modules can work at 2.3V voltage without a risk of damage.
Like all other modules from Patriot, these are equipped with traditional black-anodized aluminum heat-spreaders that are not flat but have a few, even though small, ribs. This allows the marketing people from Patriot to claim that their products provide improved heat dissipation.
The marking and default timings of the product are printed on the stickers glued to the heat-spreaders.
The SPD chip contains somewhat different info for the sake of better compatibility with mainboards.
This memory kit is inferior to the other kits in this review at practical use:
It is only stable at 915MHz with 4-4-4-12 timings. When you select 5-5-5-15 timings, the kit overcomes the 1GHz mark, but not by as much as we have seen in the tests of DDR2 SDRAM modules based on Micron chips. Note also that the frequency potential of the Patriot PDC22G8000ELK modules grows up along with their voltage.
The second memory kit from Patriot to be tested in this review is called PDC22G8000+XBLK. Products from this manufacturer marked as “XBLK” are two-module kits that are able to work at high frequencies with low latencies. The Patriot PDC22G8000+XBLK kit, in particular, is not just capable of working at 1GHz, but with 4-4-4-12 timings at 2.2V voltage. The kit consists of two 1GB DDR2 SDRAM modules.
The heat-spreaders installed on the modules are not just aluminum bars, but have some ribbing. This enlarges the surface area to improve heat dissipation. Perhaps this is the reason why Patriot’s PDC22G8000+XBLK memory, based on widespread chips from Micron, features such extraordinary characteristics.
Besides the model name, capacity, default bandwidth and frequency, the module marking that you can read on the sticker offers some extra information. Particularly, it says that the Patriot PDC22G8000+XBLK can be used at 667MHz with 3-3-3 timings, which is an indication of a certain versatility of this DDR2 SDRAM kit.
The information written into the modules’ SPD unit differs from the official specification. The manufacturer took care to make the modules compatible with different mainboards, leaving the option of correctly setting them up to the user.
So, the SPD chip stores information about using the module at 400, 533 or 800MHz.
As for practical tests, the Patriot PDC22G8000+XBLK modules proved to be the fastest among all the memory kits included in this review.
They stopped just a little short of 1067MHz at 4-4-4-12 timings, but notched 1145MHz at 5-5-5-15 timings. Note that the Patriot PDC22G8000+XBLK kit remained stable at the highest frequency (among the tested memory kits) at 3-3-3-10 timings, although couldn’t reach the 800MHz point. The maximum stable frequency was 775MHz at such timings.
So, high-frequency DDR2 memory does its job well on the Core 2 Duo platform. A majority of PC2-800 and faster modules currently offered by the manufacturers of overclocker-friendly memory prove to be stable at a frequency of 1GHz and higher, often with not very bad timings.
Modules based on Micron’s chips stand out among the tested products. Such DDR2 SDRAM modules are not only capable of working at ultra-high frequencies, but are also stable at frequencies above 1000MHz with 4-4-4-12 timings. So, memory of that type can be viewed as versatile because all DDR2-800 SDRAM for overclockers available on the market supports timings no better than 4-4-4-12.
Also remarkable is the fact that you can be as lucky as to make your Micron chips based memory work as DDR2-800 with 3-3-3-10 timings, but there is no absolute stability in that mode. Quite a lot of applications would run normally, but special-purpose heavy tests that we use to check out memory stability, especially S&M and Prime95, report possible problems. Overclocker-friendly DDR2 SDRAM also reacts well to a voltage increase – its frequency potential grows up at that. The manufacturers use this property to produce their enthusiast targeted memory. As a result, all the memory kits we tested in this review could work at 1067MHz, their voltage being increased from JEDEC’s 1.8V to 2.2-2.3V. Some memory on Micron chips could even be clocked at a fantastic 1150MHz at their default 2.2V voltage!
The Corsair TWIN2X2048-8500C5, OCZ DDR2 PC2-8000 Platinum Extreme Edition and Patriot PDC22G8000+XBLK memory kits are undoubtedly our choice. We recommend them for all enthusiasts who are going to overclock their Core 2 Duo systems. These versatile 2GB kits of DDR2 SDRAM help achieve maximum performance upon increasing the FSB frequency to 400MHz and higher.