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Corsair Dominator TWIN2X2048-8888C4DF
Date: Sep 15, 2006
Author: Marco Chiappetta
Introduction and Specifications

Over the years, Corsair has earned a solid reputation in the PC enthusiast community for consistently offering some of the best system memory kits in their respective classes. Corsair has a myriad of memory kits available in many different capacities and speeds, and virtually all of them rate well versus their competition.

Some of Corsair's most sought after modules are the "low-latency" kits in the company's XMS product line. Low-latency memory typically offers better overall performance than similarly clocked memory with higher latencies, but its not easy to produce high-speed memory kits that also have low-latencies, especially when it's DDR2 DRAM. Corsair was first to release a 2GB DDR2 memory kit that was rated for reliable CAS3 operation at DDR2-800MHz, and now the company is building upon that product with a patent-pending tweaked PCB and custom cooling solution that allowed Corsair to produce a DDR2 memory kit capable of running at 1111MHz with tighter timings than anything else currently available.

In this article, we'll be shining the spotlight on Corsair's Dominator TWIN2X2048-8888C4DF memory kit (2GB, 2x1GB DIMMs). These PC2-8888 DIMMs are high-capacity and are capable of running with a CAS Latency of 4, a RAS to CAS Delay (tRCD) of 4, a Row Precharge (tRP) of 4 and an Active to Precharge Delay (tRAS) of 4 (4-4-4-12-2T) at 555MHz (DDR2-1111MHz).

Specifications of the Corsair TWIN2X2048-8888C4DF
Tight Timings & Some Bling

"The Dominator Series Twin2X2048-8888C4DF is a 2048 MByte matched pair of DDR2 SDRAM DIMMs built using Corsair's latest high performance heat sink with Dual-Path Heat Xchange (DHX) technology coupled with a Corsair Dominator Airflow Fan. This part delivers outstanding performance in the latest generation of dual-channel DDR2-based motherboards. It has been tested extensively in multiple DDR2 motherboards to ensure compatibility and performance at its rated speed. This memory has been verified to operate at 1111MHz at latencies of 4-4-4-12-2T at 2.4 VDIMM. The Twin2X2048-8888C4DF comes with Enhanced Performance Profiles (EPP), the open standard for performance module SPD's jointly developed by Corsair and NVIDIA. EPP SPD's on Corsair modules allow users to automatically configure EPP enabled motherboards with aggressive memory performance settings, for maximum memory and system performance."

Test Specifications:

  • Each module pair is tested together at 1111MHz
  • Tested and packaged in pairs
  • Packaged together immediately following system test
  • Tested at EPP SPD settings (4-4-4-12-2T ) at 2.4V at 1111MHz
  • SPD programmed at: JEDEC standard 5-5-5-18 values at 800MHz
  • EPP standard 4-4-4-12-2T, 2.4V values


  • 2048 Megabytes of DDR2 memory
  • Two matched CM2X1024-8888C4D modules
  • Corsair 's proprietary DHX technology dissipates heat two ways: it draws heat away from the module through the RAMs and provides an additional path for heat transfer within the module through the ground plane.
  • SPD includes Enhanced Performance Profiles (EPP) which allow automatic overclocking to aggressive performance settings.
  • Comes with Dominator Air flow Fan for maximum thermal transfer
  • 100% tested at 1111MHz in high performance DDR2 motherboards
  • Lifetime warranty

Corsair's Dominator Fan

There are two members in Corsair's initial "Dominator" product line-up, the TWIN2X2048-8500C5D and the TWIN2X2048-8888C4DF. The 2GB TWIN2X2048-8500C5D kit (1GB x 2) is rated for DDR2-1066MHz operation with 5-5-5-15-2T timings. The TWIN2X2048-8888C4DF kit, which we'll be taking a look at here, however, is rated for DDR2-1111MHz operation with tighter 4-4-4-12-2T timings, and it ships with the "Dominator" fan assembly pictured here.

The Dominator fan assembly is constructed of aluminum, with three 4cm fans.  It mounts to the clips that typically hold system RAM in place and connects to a single 3-pin fan plug, so the fans can be throttled if your motherboard has the capability to control fans based on temperature.  In practice, we found the Dominator fan to be easy to install and relatively quiet, but in our open-air test bench its effect on temperature was difficult to quantify. Corsair claims the Dominator fan will reduce operating temperatures by a few degrees (from 15.4oC to 11.3oC above ambient in Corsair's testing), which will increase stability and overclockability.  The only issue we had with the Dominator fan is that it cannot be installed properly on motherboards where the DIMM slots are in-line with the PEG slot and a long graphics card is installed.  This is a mistake fewer and fewer motherboard manufacturers are making though, so it shouldn't be an issue for many of you.

Up Close and Personal

At first glance, Corsair's new flagship memory looks much the company's "Pro" branded products minus the activity LEDs, but the Dominator TWIN2X2048-8888C4DF kit is actually quite different than anything previously offered by Corsair.


There are four key things at work in Corsair's Dominator TWIN2X2048-8888C4DF memory kit that result in the product you see pictured above. As we mentioned earlier, this memory is based on the same PCB used in Corsair's low-latency TWIN2X2038-6400C3 memory kit. With the Dominator series, however, the PCB has been heightened and there are thermally conductive vias and traces running through the PCB and connected to the ground plane, to help dissipate heat from within the board itself.  Heatsinks are then bonded to both sides of the upper portion of the PCB to further aid in heat dissipation.

The memory chips on both sides of the PCB are also outfitted with their own dedicated, newly designed, oversized heatsinks to help cool the chips as well.  Having two paths from which heat can be drawn out of the modules is what Corsair is calling DHX technology, or Dual-Path Heat Xchange. And the Dominator fan featured on the previous page is the third component that aids in cooling, which in turn enhances stability, longevity, and overclockability.

In addition to DHX, Corsair is meticulously binning the memory chips used on the Dominator kits and is using only select samples that can operate reliably with low-latencies and higher clocks. The culmination of Corsair's efforts is a 2GB memory kit that's rated for operation at over 1.1GHz. We should note, however, that the TWIN2X2048-8888C4DF memory requires 2.4v to operate at its rated speed. That's a lot of voltage, and many motherboards don't offer DDR2 voltages quite that high.

Lastly, we should mention that the Dominator TWIN2X2048-8888C4DF memory is equipped with EPP, or Enhanced Performance Profiles. Enhanced Performance Profiles can increase performance by taking advantage of additional memory parameters added to the unused portion of a standard JEDEC Serial Presence Detect, or SPD ROM.  The JEDEC specification only calls for small amount of data to be stored in a standard SPD, which leaves a significant amount of unused space.  EPP takes advantage of this space to store specific information about the modules, like their maximum supported frequencies and timings.


Although the Dominator TWIN2X2048-8888C4DF memory has four distinct heatsinks and a taller-than-usual PCB, the DIMMs aren't all that much bigger than more traditional DIMMs, as you can see.  Of course, the Dominator DIMMs are taller then most others, but they're actually a little thinner than memory with typical heat spreaders. We don't think clearance will be an issue in any standard system, SFF user's however, may want to ensure you've got the room in your chassis.

Compatibility and Our Test Systems

Compatibility Testing: Before we sat down in front of our test machine to evaluate Corsair's TWIN2X2048-8888C4DF memory modules, we installed them into some of the systems we had available at the time to see if there were any compatibility problems to speak of.  We tried the sticks in a total of 5 different systems, powered by various popular chipsets, and encountered only one problem. We tested these modules on the following platforms...

Brand Model Chipset
Asus CrossHair nForce 590 SLI
Asus P5N32-SLI SE nForce 4 SLIX16
Asus P5B Deluxe Intel P965
Intel D975XBX Intel 975X Express
Abit AB9 Intel P965

With the exception of the Asus P5B Deluxe, which we used for the benchmarks in this article, to quickly test these modules all we did was install them, power up the systems, made sure Windows XP booted and we ran SiSoft SANDRA's burn-in wizard for a few minutes. The only board that had an issue was the Abit AB9. This board defaults to a 1.8v memory voltage, and wouldn't POST reliably when we first installed the Dominators. But by popping in an OCZ memory kit, raising the memory voltage in the BIOS, and then re-installing the Dominators, we were able to use them on the AB9.  This limited compatibility testing wasn't extensive, but it does bode well for the TWIN2X2048-8888C4DF memory modules. The fact that they worked properly on the popular platforms listed here, means most consumers shouldn't have any major issues with them either.

HotHardware's Test System
Not all are created equal...
Core 2 Extreme X6800

Asus P5B Deluxe
Intel P965

Corsair TWIN2X2048-8888C4DF
Corsair TWIN2X2048-8500C5
OCZ PC2-8000 Platinum 2GB

GeForce 7900 GTX
On-Board 10/100/1000 Ethernet
On-Board Audio

WD "Raptor" 74GB Hard Drive
10,000 RPM SATA

Windows XP Pro SP2
Forceware v91.47
DirectX 9.0c

How we configured our test systems:  When configuring our test system for this review, the first thing we did was enter the system BIOS and set the motherboard to its "High-Performance Defaults".  The hard drive was then formatted, and Windows XP Professional (SP2) was installed. When the installation was complete, we installed all of the necessary drivers for our components, and removed Windows Messenger from the system.  Auto-Updating and System Restore were also disabled, and we setup a 768MB permanent page file on the same partition as the Windows installation.  Lastly, we set Windows XP's Visual Effects to "best performance", installed all of our benchmarking software, defragged the hard drives and ran all of the tests. Throughout all our benchmarking, we had the memory voltage set to 2.4v, unless otherwise noted.

Stock Performance

We began our testing with SiSoftware's SANDRA, the System ANalyzer, Diagnostic and Reporting Assistant. SANDRA consists of a set of information and diagnostic utilities that can provide a host of useful information about your hardware and operating system.  We ran SANDRA's Memory Bandwidth test on a Core 2 Extreme X6800 powered test bed with three different brands / types of memory installed.  The BIOS was set to AUTO for these tests, so the different RAM modules were being run at standard JEDEC DDR2-800 specifications here.

Performance Comparison with SiSoft SANDRA 2007
Raw Bandwidth

Without tweaking the BIOS in any way, each of the memory kits performed similarly in SANDRA's memory bandwidth benchmark.  Only a few megabytes per second separated the various kits in either test.

Performance Comparison with PCMark05
Overall Memory Score

For our next round of benchmarks, we ran the Memory performance module built-into Futuremark's PCMark05. For those interested in more than just the graphs, we've got a quote from Futuremark that explains exactly what this test does and how it works...

"The Memory test suite is a collection of tests that isolate the performance of the memory subsystem. The memory subsystem consists of various devices on the PC. This includes the main memory, the CPU internal cache (known as the L1 cache) and the external cache (known as the L2 cache). As it is difficult to find applications that only stress the memory, we explicitly developed a set of tests geared for this purpose. The tests are written in C++ and assembly. They include: Reading data blocks from memory, Writing data blocks to memory performing copy operations on data blocks, random access to data items and latency testing."


Once again, all of the memory kits we tested performed similarly in PCMark05's memory test module. As we've mentioned, without specifying timings and frequencies, the motherboard ran each memory kit at the same settings, which resulted in a dead-heat in this test.

In-Game Performance Comparisons
System Memory Affects Framerates?  You Betcha!

We continued our testing with some low-resolution F.E.A.R. tests. Despite the fact that this is a game benchmark that can be used to test the relative performance of video cards, frame rates are strongly influenced by processor speed and available memory bandwidth, especially at low resolutions, which is how we ran the tests to get the frame rates listed below.

There was only a three frame per second spread in our low-res F.E.A.R. benchmarks, which falls well within the margin of error in this test. Things are likely to change once we dial in each kit for their rated speeds, however.

Performance @ Rated Speeds

Next, we continued testing with SiSoftware's SANDRA, but we manually set the memory timings on the Corsair TWIN2X2048-8888C4DF modules to their rated settings of 4-4-4-12 (CAS Latency = 4T, RAS to CAS Delay (tRCD) = 4T, Row Precharge (tRP) = 4T, Active to Precharge Delay (tRAS) = 12T) at 1110MHz. We achieved these speeds by dropping our CPU's multiplier to 8 and raising the FSB to 370MHz with a 2:3 FSB to memory speed ratio.  The end result was a CPU clock speed of 2968MHz.

We performed a similar procedure for the Corsair TWIN2X2048-8500C5 and OCZ PC2-8000 Platinum memory kits as well, but there were slight differences in the CPU speed in the end. To hit 1066MHz with the Corsair 8500C5 kit (5-5-5-15), we dropped the multiplier to 8 and raised the FSB to 356MHz, which resulted in a 2848MHz CPU clock.  And for the OCZ kit, which is rated for 1000MHz at 5-5-5-15, we dropped the multiplier to 9 and raised the FSB to 334MHz, for a final CPU clock of 3006MHz.

Performance Comparison with SiSoft SANDRA 2007
Raw Bandwidth



When running at their rated speeds and timings, each memory kit's performance increased significantly.  Thanks to its tighter timings and higher clock speed though, the new Corsair Dominator TWIN2X2048-8888C4DF memory clearly put up the best numbers at about 7.3GB/s in both tests. The others weren't too far behind, however.

Performance @ Rated Speeds (Cont.)

In this next round of benchmarks, we re-ran the Memory performance module built-into Futuremark's PCMark05 with each set of modules set to their rated frequencies and timings

Performance Comparison with PCMark05
Overall Memory Score


Corsair's new Dominator TWIN2X2048-8888C4DF kit posted the highest score in PCMark05's memory performance module a well. The Dominator TWIN2X2048-8888C4DF kit outpaced the 8500C5 and OCZ PC2800 kits by 105 and 287 points, respectively.

In-Game Performance Comparisons
System Memory Affects Framerates?  You Betcha!

We continued testing these modules with some low-quality F.E.A.R. benchmark runs while the systems were running at their rated speeds as well.

Because we kept our processor's clock speed as close to "stock" as possible while altering the memory's speed and timings, performance didn't jump dramatically in the F.E.A.R. benchmark.  The Dominator TWIN2X2048-8888C4DF kit technically offered the best performance, but the delta separating the systems was only 6 frames per second.

Performance @ Highest Overclock

For our next set of numbers, we focused on the maximum overclockability of Corsair's Dominator TWIN2X2048-8888C4DF memory kit while set to its rated timings.  Using a Core 2 Duo Extreme X6800 CPU, we raised the Front Side Bus speed while concurrently lowering our processor's multiplier.  We tried to keep the CPU as close to it's stock 2.93GHz clock speed as possible.  For these tests, we locked the PCI Express clock to 100MHz, raised the CPU voltage to 1.35v, and kept the memory voltage to 2.4v.

Overclocked Performance with SiSoft SANDRA 2007
Raw Bandwidth


When all was said and done, we were "only" able to bring the Dominator TWIN2X2048-8888C4DF kit up to 1158MHz, an increase of 48MHz.  Had we relaxed the timings and applied more voltage, we likely could have gone higher, but we wanted to test a worst case scenario and 2.4v is already a relatively high voltage to be working with.  While overclocked, we re-ran the SANDRA memory bandwidth benchmark and saw only marginal increases in bandwidth.

Performance @ Highest Overclock (Cont.)

We also re-ran the PCMark05 memory performance and F.E.A.R. benchmarks again with the Corsair Dominator TWIN2X2048-8888C4DF memory modules overclocked to DDR2-1158MHz on our Intel Core 2 Extreme X6800 powered test bed...

Overclocked Performance with PCMark05
Overall Memory Score


An additional 48MHz netted an increase of only 8 points in PCMark05's memory performance benchmark. When compared to the default scores, however, we see an increase of over 1000 points.

In-Game Performance while Overclocked
System Memory Affects Frame rates?  You Betcha!

Performance in the F.E.A.R. benchmark didn't change much with the higher memory clock either.  In fact, we'd attribute the extra 1 frame per second to the slightly higher processor frequency, and not to the small increase in memory bandwidth offered by the 48MHz increase.

Our Summary and Conclusion


Performance Summary: As expected, Corsair's new Dominator TWIN2X2048-8888C4DF memory was the fastest of the three memory kits we tested here thanks to its combination of high-capacity, relatively low latencies, and high frequency. In SANDRA's memory bandwidth benchmark it put up the highest bandwidth numbers, and it similarly posted the highest scores in the PCMark05 and F.E.A.R. benchmarks as well.

We have to give credit where credit is due, and praise Corsair for delivering and innovative, high-performance product in the Dominator TWIN2X2048-8888C4DF memory kit. The R&D put in to develop DHX and the tweaked PCB seems to have paid off, as the Dominator TWIN2X2048-8888C4DF memory kit is the fastest currently available. At almost $600 though, this is some expensive stuff.  We suppose if money is no object, overclockers can't do much better than the Dominator TWIN2X2048-8888C4DF kit, but we know many of you are cringing at the idea of spending $600 for 2GB of memory, when slightly lower performing kits are available for half the price. The bottom line however, is that the Dominator TWIN2X2048-8888C4DF memory kit is an excellent product. It's fast, flexible, innovative, and it should work fine on any platform.  We're giving the Dominator TWIN2X2048-8888C4DF kit a 9 on the Heat Meter. Whether or not it's worth $600 is a question, we'll let the market answer.


  • Innovative Cooling
  • EPP Support
  • Ultra-High Clocks
  • Tight-Timings
  • Very Expensive
  • Marginal Performance advantages

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