Corsair TWIN2X1024-8000UL Memory Modules Review

Today you will get acquainted with another memory solution that managed to surpass 1GHz threshold. It is going to be overclocker DDR2 SDRAM memory from Corsair. This memory manufacturer is very well-known for their excellent products. For example, their DDR2-1000 modules boast the lowest latencies than the competitors.

by Ilya Gavrichenkov
09/22/2005 | 02:00 AM

As we have promised, we continue introducing to you new DDR2 SDRAM memory modules. Today we are going to talk about another solution from Corsair, which we haven’t managed to include in our previous DDR2 article. I this review we are going to specifically dwell on the memory modules capable of working at 1GHz frequency.


Some time ago we already tested overclocker memory kit from Corsair, the TWIN2X1024A-5400UL (for details, please see the article called DDR2 SDRAM for Overclocking Fans: Getting Beyond 1GHz ). This product proved capable of working at 667MHz frequency and aggressive timing settings as well as at frequencies close to 1GHz. However, Corsair doesn’t really position this memory solution as a high-frequency product. There is another product, specifically designed for operation at high frequencies: Corsair DDR2 SDRAM TWIN2X1024-8000UL. This particular memory kit is going to be the hero of our today’s review.

I would like to clarify why we pay so much attention to Corsair memory modules on our site these days. This manufacturer offers the whole lot of interesting products, which attracted out attention. Besides, there are some reasons to consider Corsair one of the most popular overclocker memory modules maker nowadays. Take, for instance, the statistics of the popular CPU-Z diagnostic utility. As of September 20, 2005, Corsair memory is used in 11.8% of all systems registered in this database with the total number of records approaching 40,000.

So, if you are looking for overclocker DDR2 SDRAM, you should definitely consider Corsair memory solutions at least among the top priority choices. So, we felt like we really had to fill in the gap in our memory section with a new detailed review of such a flagship product as Corsair TWIN2X1024-8000UL.

Closer Look

DDR2 SDRAM kit from Corsair - Corsair TWIN2X1024-8000UL – consists of two identical memory modules, 512MB each, certified to work at 1GHz frequency and preliminarily tested on an Intel 955X based mainboard. Note that Corsair doesn’t offer any solutions of larger capacity identical to TWIN2X1024-8000UL: the 2GB overclocker kits from Corsair cannot boast such attractive specifications. Corsair TWIN2X1024-8000UL kit is shipped in a traditional plastic package, which contains the modules themselves and the illustrated quick installation guide with some hints about proper installation of the memory modules into the DIMM slots.

The memory modules are covered with Corsair’s standard heat-spreaders of glossy black color. There is a white inscription of the Corsair’s official web-site URL on the heat-spreaders:, and a few stickers. One of these stickers with Corsair and XMS2 logos is for decoration only, while the other one is certainly more informative. It tells the module marking, its capacity, nominal frequency and timings.

Here I would like to say that even though the modules we are reviewing today are called Corsair TWIN2X1024-8000UL, each of the modules from the kit has its own individual name: CM2X512-8000UL. This is the product marking that is given on the stickers. As for the general name of the entire kit, you can only see it on the back side of the plastic package.

We checked out the manufacturer’s web-site to find out the complete official list of technical specifications for our today’s hero. To tell the truth, the corresponding document that we discovered on Corsair’s web-site surprised us with very strange errors, so that we got the impression that it was put together in a hurry, which is not typical of Corsair at all.

Luckily, the mismatch with the names seems to be the only grave error here. Here are the major specifications of the product we are reviewing today:

I would like to stress that all previously reviewed DDR2 SDRAM modules designed for 1,000MHz working frequency featured 5-5-5-15 nominal timing settings. Corsair wanted to prove once again their reputation of a successful DDR2 overclocker memory solutions developer, so they made their 1GHz memory support more aggressive timings. The nominal RAS# to CAS# Delay and RAS# Precharge parameters have been set one clock lower.

However, Corsair TWIN2X1024-8000UL is based on the same Micron D9DQT chips as many other DDR2 SDRAM modules out there. Micron made these chips capable of working at 667MHz with CAS# Latency set to 5, however, their potential grows up dramatically once the voltage is increased. This is exactly the peculiarity many overclocker DDR2 memory makers take advantage of. Namely, they set the nominal voltage for their DDR2 memory solutions to 2.1V-2.2V.

Thus the nominal voltage of Corsair TWIN2X1024-8000UL memory modules is 2.2V. It is 22% higher than the voltage set in the official DDR2 specification: 1.8V. By the way, if they had resorted to the same voltage increase for the DDR-I SDRAM overclocker memory solutions, these modules would have been running at 3.05V today. So, Micron D9DQT memory chips not only boast great overclocking potential, but also are extremely robust against long-term functioning at higher voltage rates. It is not for nothing that all overclocker DDR2 SDRAM DIMMs have life warranty.

The SPD of Corsair TWIN2X1024-8000UL memory modules reports the following:

The SPD of these memory modules contains two sets of parameters for work as DDR2-800 and as DDR2-540. There is a very serious reason behind this difference between the SPD specifications and the official spec. The thing is that when you install the memory modules into your system and boot it for the first time, the mainboard may very often try to set the SPD parameters for these memory modules. Of course, the voltage wouldn’t be increased in this case. Therefore, if there were overclocker settings already prerecorded in the memory modules SPD, they wouldn’t work with default settings at all in a number of mainboards. Corsair TWIN2X1024-8000UL doesn’t have any compatibility issues like that due to pretty loyal SPD settings. These settings prove operational without raising the voltage even a little bit. As for the performance of these memory modules during overclocking, you can adjust the settings yourself in the BIOS Setup, keeping in mind that you need to increase the memory voltage accordingly in order to achieve high performance results.

Testbed and Methods

We assembled the following system for our performance tests of Corsair TWIN2X1024-8000UL DDR2 overclocker memory:

The mainboard BIOS contained the following settings:

This is exactly the same system as the one we used to test other overclocker memory modules. Therefore, we will be able to compare the results we will obtain today with those numbers we got earlier during our previous test session.


We tested the stability of the memory subsystem in two stages. First we ran the Memtest86+ version 1.60 to see if there were no failures during the test. Then we double checked the result in Windows XP with the S&M utility version 1.7.3 and Prime95 version 24.13. This “double-testing” allowed us to make sure that the results were credible.

Since Corsair TWIN2X1024-8000UL works at the nominal 2.2V, we carried out all our tests at this particular voltage setting, even though it seems much higher than the official JEDEC approved voltage and is not supported by all mainboards.

Our test results demonstrated that Corsair TWIN2X1024-8000UL memory modules can be regarded as highly universal. They worked just fine at 667MHz frequency with the minimal timing settings, and could easily reach 1GHz bar with higher timings. Is it surprising? Not at all! If you remember, we said exactly the same thing about all other overclocker DDR2 SDRAM based on Micron D9DQT memory chips. This is exactly the reason why all overclocker DDR2 SDRAM modules claimed to support 1GHz working frequency are so similar in action.

Nevertheless, we can still point out a few differences in the functioning of memory modules by different manufacturers. Firstly, different memory makers use different PCBs for their DIMMs, which can be better or worse protected against EMI. Secondly, the heat dissipation might be different. And thirdly, the manufacturers may have different criteria for memory chips selection. For example, Corsair offers not only their high-end TWIN2X1024-8000UL overclocker kit, but also slower overclocker modules and memory solutions for common mainstream users. This allows the company to make sure that only the best of the best DDR2 chips go into their TWIN2X1024-8000UL DIMMs.

As a result Corsair TWIN2X1024-8000UL memory modules perform very well with “average” timings of 4-4-4-12. In this workmode the memory remains stable up to 964GHz frequency. And if we increase CAS# Latency to 5, it will go beyond 1GHz. So, we have every right to state that the practical features of Corsair TWIN2X1024-8000UL not only correspond to the claimed specification, but even boast some ”reserved potential”.

If the timings are set to less aggressive 5-5-5-15, the potential of Corsair memory modules doesn’t grow that much. In this case they can only remain stable at 1028MHz maximum. Unfortunately, Corsair TWIN2X1024-8000UL failed to get beyond the psychologically important limit of 1066MHz, which would automatically qualify this memory for use in synchronous mode in systems based on top Pentium 4 Extreme Edition CPUs. Moreover, they do not manage to conquer this frequency barrier even if the voltage is set to 2.3V.

However, I suggest that we compare Corsair TWIN2X1024-8000UL against some other DDR2 SDRAM products for overclockers out there before making any conclusions. The graph below shows the results obtained not only for our today’s hero, but also for a few other overclocker solutions we have tested lately. All the memory modules included into this comparative graph worked at their nominal voltage. Besides, you can also see what frequencies can be achieved by the testing participants in case the voltage is increased to 2.3V, which was the maximum voltage our mainboard supported.

So, Corsair TWIN2X1024-8000UL looks pretty impressive against the competitors’ background, I should say. In most cases this memory proved capable of working at higher frequencies than the rivals without losing the system stability. The advantage of Corsair TWIN2X1024-8000UL is especially evident with the “average” 4-4-4-12 settings. In this case our today’s hero is more than 50MHz faster than the competitors. And even though there are situations when Corsair TWIN2X1024-8000UL doesn’t actually win the race, it is not that far behind the leader at all.

So, I can conclude with all certainty that Corsair TWIN2X1024-8000UL memory modules can ensure notably higher performance during overclocking of your LGA775 system in most cases. If you are looking for more details on how the latency settings and DDR2 frequency can actually affect the overall system performance, I suggest that you refer to our article called DDR2 SDRAM for Overclocking Fans: Getting Beyond 1GHz.


We have just reviewed another overclocker DDR2 SDRAM kit built of Micron D9DQT chips. This time these were the memory modules from Corsair capable of overcoming the 1GHz threshold. Even though Corsair TWIN2X1024-8000UL memory is very similar to the previously reviewed competitor solutions, it proved to be a little better. It is better not only by the specs: it is claimed to support 1GHz frequency at more aggressive timings of 5-4-4-9. The practical results also suggest its superiority over the rivals, as we have just seen from the performance graph above.

Here I would also like to add that thanks to the smart SPD record, Corsair TWIN2X1024-8000UL modules do not suffer from any compatibility issues, which are still a problem for a few competitor solutions.

So, Corsair TWIN2X1024-8000UL memory can become an excellent choice for overclocker systems based on LGA775 processors. This memory works great at high frequencies and supports aggressive timing settings at relatively low working rate. The only thing I could actually consider a drawback of Corsair TWIN2X1024-8000UL (not taking into account their price) is probably the required higher voltage of 2.2V, otherwise, these memory modules won’t boast their brilliant performance any more.