Roundup of 2GB DDR SDRAM Memory Kits for Overclockers

High capacity fast DDR SDRAM for overclocking enthusiasts is no longer a rare thing to see these days. The leading memory manufacturers have finally started offering more and more kits of the kind. In our today’s roundup we will take a closer look at 2GB DDR SDRAM kits from Corsair, OCZ, G.Skill and PQI.

by Ilya Gavrichenkov
02/10/2006 | 04:42 PM

The analysis published on our site a few days ago called 2GB of RAM: Do We Really Need That Much? proves that there already exist tasks for which 2 gigabytes of system memory make a difference. Since not only heavy professional applications, but also some contemporary games belong to this category, it’s time to get serious about equipping your new high-performance platform with as much as 2 gigabytes of RAM.


We also showed you how negative it may be to use four DIMM modules on an Athlon 64 platform. First, when four modules are in use, the integrated memory controller automatically uses a Command Rate of 2T rather than 1T. The performance hit may be as big as 5-10% as a consequence. Second, the overclockability of the system worsens with four DIMM modules since the maximum stable clock-generator frequency is lower. These things considered, memory modules of 1GB capacity seem to be the best choice for today’s top-end platforms.

That’s why we have to revise our memory testing priorities and shift the focus towards 2GB DDR SDRAM kits that consist of two modules. In today’s review we are going to check out the most popular 2GB overclocker-friendly kits of DDR SDRAM (for dual-channel systems) the leading DRAM makers offer for PC enthusiasts. Today we will check DDR1 SDRAM that the overclockers love the most and use in platforms based around AMD Athlon 64 processors. Four manufacturers were kind to offer us their products, so we have 2GB DDR SDRAM kits from Corsair, OCZ, G.Skill, and PQI to work with.

Testbed and Methods

Besides the performance and specified characteristics of a memory module, a PC enthusiast may be interested in other things like the highest frequency the memory can work at in an overclocked computer. So this review includes not only performance but also overclockability tests of DDR SDRAM modules.

We tested stability of the memory modules in two steps. First we verified there were no errors with Memtest86+. Then we rechecked this in Windows XP with the S&M and Prime95 utilities. This two-tier control system helps ensure high reliability of the obtained test data.

The frequency graphs included into the descriptions of the memory kits show the maximum frequency the modules are stable at (as verified in the above-described manner) with the specified memory timings.

Our testbed was assembled out of the following hardware parts:

The memory subsystem was clocked synchronously with the clock generator, so we reduced the CPU frequency multiplier to 8x to avoid reaching the maximums table CPU clock rate.

And now let’s have a closer look at each of the memory kits about to be tested.

Overclocker-Friendly 2GB Kits of DDR SDRAM

Corsair TWINX2048-3500LLPRO

The Corsair TWINX2048-3500LLPRO kit consists of two 1GB DIMMs of DDR SDRAM that are rated to work at 218MHz (436MHz DDR) with aggressive timings. At least the manufacturer claims that all kits of this series are tested at that frequency and with 2-3-2-6 timings on an ASUS A8N-SLI Premium mainboard.

The memory kit belongs to a professional product series which means two things. First, Corsair TWINX2048-3500LLPRO modules are equipped with larger heatsinks. Second, on the top edge of each module there are 18 green, yellow, red LEDs indicating the memory module usage. That’s why this product has a particular appeal for modders and owners of system cases with a transparent side window – the modules do look amazing at work.

For our pragmatic minds, however, it is the large heatsink that makes these modules special. On one hand, the bigger height of the modules may cause some installation-related problems on mainboards where Socket 939 and DIMM slots are placed too closely. For example, the popular Zalman CNPS7700Cu cooler most often makes it impossible to install these sticks into the DIMMs nearest to the CPU socket. Similar problems may occur with other massive coolers. And still, we think it’s good rather than bad to have a larger heatsink with a larger dissipation area on a memory module, especially on a 1GB module which is hotter than conventional 512MB sticks. Excessive heat may even hinder your overclocking attempts at times, so we can put up with some inconveniences just to be sure about efficient heat dissipation. However, before purchasing a Corsair TWINX2048-3500LLPRO kit, you may want to make sure you can physically fit these sticks into your computer. For reference: the height of a Corsair TWINX2048-3500LLPRO module is 45 millimeters (as opposed to conventional modules’ 33 millimeters).

Let’s get back to the heatsinks, though. They have a small ribbing for better efficiency and are made of aluminum anodized into black color. The stickers on the modules tell you the name of the manufacturer and of the product series; the sticker on the other side of the module displays the Corsair logo and informs you of the basic characteristics of the modules like name, capacity, frequency and timings. Here’s the formal specification of the Corsair TWINX2048-3500LLPRO memory kit:

Note that unlike overclocker-targeted memory modules of 512MB capacity, Corsair’s TWINX2048-3500LLPRO memory works at a rather low voltage of 2.6V. Infineon’s revision B chips used for these modules have high frequency potential at this voltage.

Although Corsair positions its TWINX2048-3500LLPRO as low-frequency modules supporting aggressive timings, their default timings are slackened a little relative to 2-2-2, but as a matter of fact, no existing DIMM module of 1GB capacity supports 2-2-2 timings. Thus, the Corsair TWINX2048-3500LLPRO modules have the lowest timings among 1GB memory modules available today.

And here’s the SPD information for these modules:

As you see, the SPD chip contains the specified timings and a lower-than-specified 200MHz frequency (400MHz DDR). It means you can use the Corsair TWINX2048-3500LLPRO in new systems at the default settings.

The results of our overclocking the Corsair TWINX2048-3500LLPRO kit at the default 2.6V voltage are presented in the next diagram:

So, these modules don’t have a big frequency reserve. As you can see, we only managed to lift the memory frequency up to 225MHz (450MHz DDR). The frequency potential is higher at less aggressive timings, though. For example, we hit 250MHz (500MHz DDR) frequency at 2.5-3-3-10 timings, but this seems to be the maximum. We didn’t get any frequency gain by using bigger timings.

We must warn you that Corsair TWINX2048-3500LLPRO modules react badly to raising their voltage, which is the normal behavior of revision B chips from Infineon used in these modules. Moreover, this memory works even slower at higher voltage than it would work at the default voltage. For example, we could only achieve 233MHz frequency when overclocking it at 2.8V voltage even with not-very-aggressive timings (at the default timings the memory is operable in this case, though).

So, the Corsair TWINX2048-3500LLPRO memory kit is best used at frequencies a little over 200MHz (400MHz DDR), but with aggressive timings. These modules can’t beat high frequencies, their limit being 250MHz. This should be enough in most cases, though, especially since the integrated memory controller of Athlon 64 processors offers you usable step-down divisors to set the memory frequency.

Corsair TWINX2048-4000PT

Corsair also offered us another 2GB kit they produce, TWINX2048-4000PT. These memory modules have been shipped for much longer than the rather recently released TWINX2048-3500LLPRO. They appeared back at the times of Socket 478 systems and this is probably why the Corsair website mentions factory tests of such modules on an out-dated ASUS P4C800 mainboard. Still, you can buy a TWINX2048-4000PT kit even today, especially since it has become cheaper and thus more affordable.

These modules have the classic appearance of a Corsair product which means they have molded aluminum heatsinks that contact the chips through a special thermal pad and are additionally braced up with a steel wire clamp. The heatsinks on our modules are made of uncolored aluminum and carry the manufacturer’s logo. The same modules are also available with black anodized heatsinks for true aesthetes.

The sticker on one side of each module tells you the module’s part number, frequency, capacity, default timings. The full specification looks as follows:

Like the above-described modules from Corsair, the TWINX2048-4000PT kit doesn’t require to increase the voltage over 2.6V for normal use. It means you can use these modules on various mainboards, including those that don’t offer you the option to adjust the DIMM voltage. The chips in these modules are different, made by Samsung, so the TWINX2048-4000PT differs a lot from the TWINX2048-3500LLPRO kit.

The manufacturer positions the TWINX2048-4000PT kit as memory capable of working at high frequencies, but at rather big timings, too. These modules are not to be used with timings smaller than 3-4-4, even if you increase their power voltage.

The following is written into the modules’ SPD unit:

The SPD information is identical to the official specification. This is done without any harm to compatibility here. Moreover, Athlon 64 processors on the revision E core that support DDR500 SDRAM can work with Corsair TWINX2048-4000PT clocked at 250MHz (500MHz DDR) without any changes in the BIOS Setup.

As for the real performance of the Corsair TWINX2048-4000PT, the next diagram shows you what frequencies our sample of the kit could conquer at its default voltage of 2.6V:

So, this memory overcomes the 250-megahertz barrier at the biggest timings only (3-4-4-10). Unfortunately, you can’t use this memory kit as DDR500 SDRAM with lower timings, and this memory can’t even work at all at timings lower than 2.5-3-3-10.

Our increasing the voltage to 2.8V didn’t affect the performance of the modules in the slightest. Their frequency potential remains the same, no worse and no better. At higher voltage the memory’s characteristics degenerate, obviously due to overheating. Unfortunately, the heatsinks on the Corsair TWINX2048-4000PT are not of the enlarged variety, while the chips used for these modules become very hot at work.

The maximum frequency we achieved with the Corsair TWINX2048-4000PT modules was 265MHz (530MHz DDR). This is no record, of course, especially if you compare this to the achievements of 512MB modules, but a good result nonetheless for a 1GB DIMM.

Thus, the Corsair TWINX2048-4000PT memory is good only when you are trying to get a higher memory frequency whatever the timings may be. Note, however, that this memory is better than the new and pretty-looking Corsair TWINX2048-3500LLPRO kit in one mode only, namely at the biggest, 3-4-4 timings.

G.Skill F1-4000USU-2GBHZ

Products from G.Skill are not yet as popular and widely recognized as Corsair’s, but it doesn’t mean they don’t deserve that. G.Skill is a leading manufacturer of overclocker-friendly memory modules on Taiwan and has been in this business since 2003. The company itself dates its origin back to 1989.

The company responded to our request of a 2GB memory kit to test with its best product, F1-4000USU-2GBHZ at that time. These DDR500 SDRAM modules are in fact very similar to the Corsair TWINX2048-4000PT: they are expected to work at a rather high frequency, but with slackened timings.

The modules don’t impress you with their exterior design. They are covered on both sides with molded aluminum heatsinks of a standard shape, anodized black. The heatsinks are braced up with black metal clamps; there’s a heat-conductive pad between them and the memory chips. On the reverse side of each module there is an embossed manufacturer logo and an informational sticker with the basic characteristic of the product (part number, capacity, frequency, default timings and voltage).

Here’s the specification of the G.Skill F1-4000USU-2GBHZ kit:

The declared characteristics of the G.Skill F1-4000USU-2GBHZ modules are identical to those of the above-described Corsair TWINX2048-4000PT. The only difference is that G.Skill explicitly mentions that its memory can be used at up to 2.8V voltage. This similarity shouldn’t be surprising if you learn that the G.Skill F1-4000USU-2GBHZ are based on the same Samsung chips as Corsair’s. Thus, this kit from G.Skill is to be used at rather high frequencies and at timings relaxed to 3-4-4.

The SPD info for the G.Skill F1-4000USU-2GBHZ also reminds Corsair’s TWINX2048-4000PT.

The latencies and frequency written in the G.Skill modules’ SPD exactly comply with their specification.

Since the G.Skill F1-4000USU-2GBHZ is in fact an analog of the Corsair TWINX2048-4000PT kit, we had expected it to perform on a similar level. However, G.Skill’s kit proved its superiority at 2.6V voltage:

At the default timings of 3-4-4-10 the G.Skill F1-4000USU-2GBHZ reached a frequency of 270MHz (540MHz DDR), which is somewhat higher than the Corsair TWINX2048-4000PT kit could manage. Otherwise, the results of these two memory kits are identical. The G.Skill modules can’t work at all at latencies better than 2.5-3-3-10 and don’t support 250MHz frequency with timings other than 3-4-4-10.

The G.Skill F1-4000USU-2GBHZ memory also reacts predictably to changes in the supply voltage. At 2.8V the modules behave exactly as at the default voltage, but at higher voltages their characteristics degenerate suddenly. This memory can’t work at all at 3.0V voltage, whatever the memory bus frequency may be. We suppose this problem is caused by overheating of the memory chips the ordinary aluminum heatsink can’t cope with.

So, the G.Skill F1-4000USU-2GBHZ kit can be viewed as average-level DDR500 SDRAM modules capable of working at 250MHz (500MHz DDR) frequency with poor timings only. On the other hand, this memory overclocks well, which may come in handy for overclockers who prefer to speed up the memory bus in sync with the clock generator on their Athlon 64 systems.

OCZ PC4000 EB Dual Channel Platinum Edition

OCZ Technology doesn’t need our recommendations. Smart marketing and high-quality products have won this manufacturer universal recognition in the last few years. The OCZ PC4000 EB Dual Channel Platinum Edition modules we received for our tests are the example of a successful product that upholds the manufacturer’s reputation. Let’s examine this kit closely.

Although the OCZ PC4000 EB Dual Channel Platinum Edition kit consists of DDR500 SDRAM modules, two examples of which you have already seen above, they differ considerably from both G.Skill F1-4000USU-2GBHZ and Corsair TWINX2048-4000PT. First, they differ externally. OCZ is the only manufacturer in this review to equip its modules with copper rather than aluminum heatsinks and the PC4000 EB Dual Channel Platinum Edition can be easily distinguished from the other reviewed kits by the sheer weight alone. Then, the heat-spreaders are polished and covered with a mirror-like platinum-colored sputtering. The shape of the heatsinks is standard, though, and they are braced up with two steel clamps quite in the usual way. There’s a heat-conductive pad inserted in between the heat-spreaders and the chips. The shiny modules are surely attractive, but your fingerprints are just too visible on the mirror-like surface, so you may want to wipe them away with soft cloth after you’ve plugged the module in.

The manufacturer’s logo is embossed on both sides of each module. On the face side there is also a sticker that tells you the basic info about the product like the part number, name, frequency, capacity and timings. And here’s the biggest surprise: the characteristics of this memory from OCZ don’t look a bit similar to the specifications of other 1GB DDR500 SDRAM modules. Here they are:

The difference is fundamental: the default voltage of the modules is increased to 2.8V, but the timings are lowered down to 3-3-2-8. Of course, this is not only due to the copper heatsinks, but rather to the chips these modules are based on – revision C chips from Infineon. OCZ also mentions two special technologies implemented in these modules: Ultra Low Noise refers to the special EMI-minimizing design of the PCB, while Extended Voltage Protection allows using the module at 2.9V voltage without voiding the warranty.

The rather low timings of the OCZ memory coupled with its rather high frequency make us suspect it will be operable with the aggressive 2-3-2 timings at frequencies around 200MHz (400MHz DDR). We’ll check this shortly, though. Right now let’s have a look at the contents of the SPD chip:

Did you expect to see anything else here? The SPD info honestly copies the official specification. This should help inexperienced users deal with these modules.

We tested the OCZ PC4000 EB Dual Channel Platinum Edition kit at their default voltage of 2.8V.

Yes, these are impressive results as opposed to the performance of the other 1GB modules of DDR500 SDRAM. It seems that Infineon’s revision C chips are the best choice for 1GB DDR SDRAM DIMMs today. The OCZ PC4000 EB Dual Channel Platinum Edition memory has proved its versatility: although the manufacturer positions it as DDR500 SDRAM, it can function at the aggressive 2-3-2-10 timings, too. With these timings the modules could work at 219MHz (438MHz DDR) frequency. The maximum frequency they were stable at with the relaxed 3-4-4-10 timings was 275MHz (550MHz DDR).

This memory from OCZ reacted positively to higher voltages. For example, we made this memory work at 282MHz (564MHz DDR) with 3-4-4-10 latencies after we increased the voltage to 3.0V.

Thus, the OCZ PC4000 EB Dual Channel Platinum Edition kit is not only a universal solution for overclockers who want to use 1GB modules, but also features excellent overclockability in its class.


PQI is another memory manufacturer from Taiwan which has entered the market of overclocker-friendly memory modules after the merger with PMI. We have already introduced some PQI products to you in the past. This is another one of them. Let’s take a look at the product.

The PQI3200-2048DBL modules we received for our tests have a very peculiar appearance. The manufacturer seems to have worked on the design of the heat-spreaders each module is covered with on both sides. On the black glossy surface of the heat-spreaders there is a large mirror-like brand TURBO Memory and, in small print, a PQI logotype. These heatsinks do look unusual and differ strikingly from the typical molded bars midrange memory manufacturers put on their products.

Well, the appearance is in fact the major advantage of the heat-spreaders installed on the PQI3200-2048DBL modules. From the technical point of view, they are ordinary aluminum bars that are not even pressed down to the memory chips properly because there is no stiff fastening provided. They are held by a sticky heat-conductive film inserted in between the heat-spreaders and the chips. We noticed that the heatsinks aren’t quite snug against some memory chips on our modules and thus do not cool them at all.

On one side of each module there is a sticker with the marking, frequency, capacity and timings. The PQI3200-2048DBL kit is declared to have the following characteristics:

In other words, the PQI3200-2048DBL modules are ordinary DDR400 SDRAM capable of working at 2-3-3 timings, the most aggressive timings for 1GB modules. These modules are based on Infineon’s revision B chips which have proved their worth in the Corsair TWINX2048-3500LLPRO kit. But PQI is not Corsair yet, and we can’t expect similar results from modules with loosely fitted heat-spreaders.

The following info is contained in the modules’ SPD:

So, we’ve got the same info as in the specification. This SPD leaves a poor impression, to tell you the truth: the manufacturer didn’t even bother to fill its own name in.

The main thing, however, is how the product performs in real life. Here are the results of our overclocking experiment conducted for the PQI3200-2048DBL kit at its default voltage of 2.6V:

So, the memory from PQI can’t get a good word from us even for its performance in the tests. Yes, it is usable at the specified 2-3-2-10 timings and 200MHz (400MHz DDR) frequency, but this memory has a really tiny overclocking potential. Relaxing the timings doesn’t help as the maximum frequency achieved is only 215MHz (430MHz DDR). This is far worse than Corsair’s modules on analogous chips have done. The sloppy heatsink design or maybe something else led to this result.

We couldn’t improve the results of the PQI3200-2048DBL kit by increasing the supply voltage. The frequency potential worsens at 2.8V voltage. At 3.0V the modules can’t start up even at the default 200MHz settings whatever timings you may choose.

So, the PQI3200-2048DBL kit appeared a disappointment. This memory kit was the last one to finish the race in this review. It is only capable of working at frequencies near 200MHz (400MHz DDR).


It should be noted that the descriptions of the modules and their overclockability tests carry enough information for you to make your choice, but we want to complement these data with the results of performance tests of systems equipped with that memory at the settings recommended by the manufacturers. The tests were performed on the same system that we used for our overclocking experiments.

The memory frequency is always set in sync with the clock generator. That’s why we again had to play with the CPU frequency multiplier:

So, all the memory kits were tested under identical conditions; the performance of the systems depended only on the frequency and timings of the memory subsystem. These tests will help us choose the highest-performing kit among the reviewed ones, considering that they all have different frequencies and latencies.

First, we want to run some synthetic tests that are specifically designed to measure the memory subsystem performance.

Quite expectedly, the real bandwidth provided by different memory modules depends directly on the memory frequency. So, the results of the tests aren’t surprising at all.

As for the measured latency, it’s not all so obvious. Latency depends both on the timings and the frequency. That’s why the OCZ PC4000 EB Dual Channel Platinum Edition kit wins the latency test as this memory features rather aggressive timings of 3-3-2-8 and works at 500MHz. The second and third places go to the other DDR500 SDRAM modules, from Corsair and G.Skill, that work with 3-4-4-8 timings.

And now let’s check the 2GB memory kits in real-life applications.

The results agree with what we have seen in the synthetic tests. The OCZ PC4000 EB Dual Channel Platinum Edition modules with their good timings and rather high frequency and the Corsair TWINX2048-3500LLPRO kit with its excellent timings and good frequency are the best here. However, the real-life tests suggest that your choice of the memory modules doesn’t affect the performance of the computer much. That’s why we think the frequency potential of overclocker-friendly memory modules is more important than their performance.


We’ve tested five 2GB memory kits and arrived at some points worth mentioning.

First of all, we want to say that 1GB DDR SDRAM memory modules (that make up 2GB memory kits) can’t match the characteristics of 512MB modules. The popular lower-capacity modules have better overclockability and can work at more aggressive timings, too. But as we’ve found in our previous reviews, you sometimes don’t have a choice as there are a number of applications that require as much as 2GB of system memory. It is not recommended to use four 512MB modules due to the automatically activated 2T Command Rate setting and the considerable worsening of the mainboard’s overclockability. So, in some cases 1GB DDR SDRAM modules have no alternative and you have to put up with their not-very-impressive characteristics.

Among the numerous DDR memory modules with 1GB capacity available today on the market, modules on Infineon’s revision C chips seem to be the best. Such modules can work with 2-3-2 timings at frequencies near 200MHz (400MHz DDR), with 3-3-2 timings at 250MHz (500MHz DDR) frequency, and with “bad” timings at 280MHz (560MHz DDR) and higher.

Among the products we have reviewed today, the pair of OCZ PC4000 EB Dual Channel Platinum Edition modules features such chips. And it is this memory kit that has shown the best overclockability and maximum performance in our tests.

We’d want to draw your attention to the Corsair TWINX2048-3500LLPRO kit, too. Although the overclocking potential of these modules is lower than of the OCZ PC4000 EB Dual Channel Platinum Edition, they boast better stability with the aggressive 2-3-2 timings at frequencies over 220MHz (440MHz DDR). Moreover, these modules look cute and have a LED indicator on the top edge. On the other hand, don’t forget about the possible problems that may arise due to their really huge size.

According to the results of our tests we decided to award OCZ PC4000 EB Dual Channel Platinum Edition memory modules with our prestigious Editor’s Choice Award.