Currently, the high-end memory market is splintered between DDR2 and DDR3, with Intel supporting both, while AMD is sticking with DDR2 until its next generation. The primary Intel DDR3 platforms feature the X38 and X48 Express chipsets, with default support to DDR3-1600, and unofficial support going much higher. DDR3-1600 is the current "sweet spot" for enthusiast DDR3, with special attention paid to low-latency modules in the CL7 range. Because of its design, DDR3 memory is very susceptible to latency issues, and achieving lower timings can be more beneficial than simply raising clock speeds.
Corsair offers several different DDR3-1600 memory kits, including both CL7 and CL9 memory timings, with some offering support for Intel (XMP) and NVIDIA (EPP 2.0) overclocking profiles. The Corsair TWIN3X2048-1600C7DHXIN is one of the higher-end configurations, and includes 2x1GB of XMS3 DDR3-1600 modules, rated at 1600 MHz with CL7 timings and using a 1.8V or higher memory voltage.
By default, these Corsair XMS modules operate at DDR3-1333 speeds, using CL9 timings and a 1.6V memory voltage, but are certified for 1600 MHz operation at CL7 timings. The "IN" at the end of the product name translates into Intel Extreme Memory Profile support with X38 and X48 motherboards. This feature automatically loads a profile through the BIOS, which when selected, will enable the stated 7-7-7-20 timings at 1.8V, as well as any other custom settings. End users can do it manually, but the XMP support simply makes the process easier and more seamless.
The two XMS3 modules feature a silver exterior, using the Corsair DHX (Dual-Path Heat Xchange) system, with extruded aluminum heatsinks and fins, for maximum DDR3 module cooling. The only negative with this design is that the modules are slightly taller than standard, and can be a bit more difficult to install in tight case environments. Corsair also offers a full lifetime warranty on this DDR3-1600 kit.
Since our Corsair XMS3 PC3-12800 2x1GB kit offers Intel Extreme Memory Profiles, our first step was to test the CL7 1600 MHz profile. The Crucial XMS3 boots at DDR3-1333 CL9 by default, to allow full compatibility, and it's up to the user to do any further tweaking. The Intel Extreme profile shows up automatically in the System BIOS, and once enabled, the CL7 memory timings, 1600 MHz speeds and 1.8-1.9V memory voltage setting are automatically enabled. This profile booted without issue, and we completed several lengthy test runs without issue.
Moving up to higher DDR3 clock speeds, while maintaining the low CL7 timings, was difficult, and we were unable to reach a DDR3-1800 clock at CL7 timings - even at 1.9V. To test the kit's true overclocking limits, we relaxed the timings to default CL9 levels. By using a 1.8V voltage, we were able to hit DDR3-1800 speeds, and on a more fully-featured Gigabyte X48 board, we hit DDR3-1900. We couldn't quite reach a 2000 MHz clock, but it was very close, and 1900 MHz still gave us all the overclocking headroom we'd need at CL9.
The Corsair XMS3 PC3-12800 2x1GB memory kit features Intel Extreme Memory Profiles, so naturally we're going with an Intel platform. The 3.16 GHz Core 2 Duo E8500 is one of the top performers on the planet, and it easily covers off our CPU requirement. The Intel X48 Express chipset is another slam-dunk, as it is the most powerful DDR3 desktop platform, and fully supports DDR3-1600 speeds. The Intel X38 is virtually the same chipset, but allows us the option of DDR2-1066 memory support and comparison benchmarks.
The remainder of our two Intel system configurations also keeps to the high-end of the scale, supplying a PNY GeForce 8800 GTS 512MB video card, along with a powerful Seagate 750GB SATA 3.0 Gb/s hard drive and a Cooler Master Real Power Pro 850W power supply. Our base operating system is Windows Vista Ultimate 32-bit, with recent DirectX and system updates installed.
Since we are looking to highlight memory performance, our benchmark list is tailor made for this task. We use PCMark05 Pro, PCMark Vantage, Everest Ultimate Edition 4.60, SiSoft SANDRA 2009, and WinRAR 3.80 as our primary tests. We ran a few comparison game benchmarks, but these usually rely on graphics+CPU performance and rarely highlight the memory component, so will not be included.
The first benchmarking section will deal with base memory bandwidth and subsystem performance, and will feature the very latest SiSoft SANDRA 2009 suite.
SiSoft SANDRA 2009 is the latest revision of this popular suite, and it supplies a wide range of potential benchmarks. Naturally, we're concentrating on memory performance, so are sticking with the three standard tests - Integer Memory Bandwidth, Cache and Memory, and Memory Latency. All three of these are affected by the type and speed of the system memory, and should highlight the potential performance levels.
The first chart highlights the Integer Memory Bandwidth scores of the various platform and memory combinations. The Corsair XMS3 PC3-12800 2x1GB kit scores the highest, and outpaces standard DDR2-800 by a nice margin. DDR2-1066 is a bit tougher egg to crack, and as per its bandwidth rating, competes well with DDR3-1066.
Our next benchmark is the Cache and Memory test, which demonstrates the overall performance of the CPU cache and memory subsystem. This is highly dependant on the CPU cache design, so the processor must be consistent between tests. This dependency also limits the memory component, and although the Corsair XMS3 PC3-12800 2x1GB kit posts the highest score, the gap between the memory types is not that significant.
The Memory Latency test is very interesting, and shows DDR3 with a commanding lead over DDR2, even at 1066 MHz clock speeds. The Corsair XMS3 is again the top performer, and you can easily see the latency penalty in selecting CL9 DDR3-1333 over its CL7 counterpart.
The second portion of our memory benchmarking section highlights the Everest Ultimate Edition 4.60 benchmark, and outlines the various memory and subsystem performance tests.
Everest Ultimate Edition is another very popular system application, which follows SiSoft SANDRA by offering a selection of diagnostic and benchmark utilities. We have used the very latest 4.60 version to ensure we are getting viable results on these cutting-edge platforms and memory speeds. By concentrating specifically on memory performance, we employed the following tests: Memory Read, Memory Copy, Memory Write, and Memory Latency.
The first chart outlines the Memory Read bandwidth scores for the various configurations, with the Corsair XMS3 PC3-12800 2x1GB set easily posting the top score. Here, DDR3 holds a noticeable advantage over DDR2, and even at equivalent bandwidth ratings, DDR3 wins out.
The Memory Copy benchmarking is a lot closer, and we even see dual-channel DDR2-1066 taking over the top spot, and driving our Corsair XMS3 PC3-12800 2x1GB kit down to second place.
The Memory Write testing does offer some notable performance differences based on platform, but since the Intel X38 and X48 are virtually equivalent, the overall bandwidth scores follow suit.
The Memory Latency results follow along with the SANDRA testing for the most part, and again, the Corsair XMS3 PC3-12800 2x1GB kit at CL7 easily hits the lowest memory latency.
The third and final part of our memory benchmarking section features our platforms running through the demanding PCMark05 Pro and PCMark Vantage suites, and then following that up with a quick WinRAR 3.80 bandwidth test.
PCMark05 Professional remains a popular system benchmarking suite from FutureMark, and offers some very tough system tests, including multithreaded and multi-tasking sequences. We are concentrating on the Memory Test Suite, which includes memory read, write, copy and latency testing, all at a variety of block sizes. In all testing, the latest 1.2 patch & hotfix have been applied.
The PCMark05 Pro Memory scores are hardly a surprise, and show the Corsair XMS3 PC3-12800 2x1GB matched pair with the highest overall bandwidth, followed by the DDR3-1333 CL7 results. Here, the DDR2-1066 scores are more in line with DDR3-1333 at CL9 timings.
PCMark Vantage differs greatly from previous PCMark suites in that it does not isolate system components in the same way, and will not provide us with a distinct rating on the system memory performance. It is still an important test, and from the Whitepaper, the two areas that stress the memory component the most are the PCMark and Memories (digital images) suites. For all benchmarking, we have used PCMark Vantage 1.0 with the hotfix applied.
The overall PCMark score shows a very tight battle between the DDR2 and DDR3 platforms, with the Corsair DDR3-1600 CL7 memory finally coming out on top, just ahead of the dual-channel DDR2-1066.
The Memories, or digital imaging, section of PCMark Vantage also takes a heavy toll on the memory subsystem, and again shows the Corsair XMS3 out in front. Once again, DDR3 shows a slight edge over the corresponding DDR2, with DDR3-1066 CL6 outperforming DDR2-1066 CL5.
WinRAR includes an internal, multi-threaded benchmark program that measures the performance of the RAR compression and decompression algorithm using a demanding worst-case-scenario data set. The memory speed and bandwidth combination has a direct impact on these results, and as the chart clearly outlines, the Corsair XMS3 PC3-12800 2x1GB dual-channel kit speeds out to an easy victory.
The overall benchmark results are certainly in favor of the Corsair XMS3 PC3-12800 2x1GB kit, and it wins virtually all of the memory performance and bandwidth tests. The effect of lowering the latency to CL7 is very noticeable, and even DDR3-1333 at CL9 can fall behind DDR2-1066 in many benchmarks. However, given the standard 1333 MHz FSB, the advantage of low-latency DDR3-1600 is still limited, and it may take the upcoming Nehalem platform to fully maximize the sheer bandwidth of high-speed DDR3 memory. Overall performance with the Corsair XMS3 and Intel X48 platform was very speedy, and low-latency DDR3 is still the best solution for the hardcore enthusiast.
Although DDR3 has dropped considerably in price, it remains more expensive than corresponding DDR2, especially the high-performance, low latency models. The Corsair XMS3 PC3-12800 2x1GB kit checks in at just under $200, and on par with some other CL7 DDR3-1600 2x1GB models. Competing brands like Crucial Ballistix, Mushkin XP, and OCZ Platinum/Reaper DDR3-16000 CL7 are around the same price, but you can find lower-cost, house brand DDR3, though often with higher voltage requirements and lower compatibility. DDR2 is significantly less expensive, with 2x1GB of DDR2-1066 CL5 at $50-$60, and even 2x1GB of DDR2-1200 at just under $100.
* Please note that these prices were taken at the time of review and are not meant to reflect long-term trends.
DDR3 might look like a high-priced luxury to some, but as both prices and memory timings continue to fall, it's becoming a far more attractive option for hardware enthusiasts. Add to that the high-performance Intel X48 platform, some definite performance advantages at DDR3-1600 and higher speeds, and the upcoming Nehalem platform, and DDR3 looks to have a bright future. For our money, low-latency DDR3-1600 like the Corsair XMS3 PC3-12800 2x1GB kit is the best price-performance solution, offering better-than-DDR2 bandwidth, but at prices significantly lower than similar DDR3-1800 or -2000 memory.
