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Corsair TWIN2X2048-6400 PRO Corsair TWIN2X2048-6400 PRO: A full one gig isn't enough for you? We look at a 2GB kit from Corsair and sees if you get a good return on investment.
Date: October 12, 2005
Written By:

has a reputation among enthusiasts as makers of some of the best ram in the business. Over the years, as ram technologies change, as well as getting faster, Corsair was always out there, putting out products to meet the demands of power users.

While DDR2 has been something of a hard sell for many users, it has steadily, albeit slowly, gaining acceptance among enthusiasts. With AMD slated to possibly offer DDR2 with their next-gen platform, things are looking up for the oft maligned ram format.

Now, whether you need DDR2 or plan a Pentium 4 (only 915P chipsets and up currently supports DDR2) is one decision you need to make. The second is how much of it? In our opinion, 512MB is the true minimum we consider for Windows XP, and 1GB the recommended. We've seen reports about 2GB making a bigger impact, but we feel this is something worth looking into first hand.

Today we'll be checking out Corsair's TWIN2X2048-6400 PRO kit. These modules are based on the XMS2 line, and feature a platinum coloured heat spreader and the same activity LEDs that we're familiar with in their Pro Series modules.


Part Number
CAS Latency
2x240 DIMM

You can view the full specifications in this , but what you need to know is the modules are validated with multiple Intel based motherboards at 800MHz.

The ram modules arrived in a hard plastic case, with each ram module fitted in the clear plastic shell. It's worth pointing this out is because there should be no confusion in what you're getting. You have a clear view of the ram, and the labels (indicating the type of modules), and the packaging is snap sealed. The seal changes to a slightly translucent white when opened, so it should be pretty obvious to the buyer if the package has been tampered with.

The XMS2 Pro Series modules have platinum coloured heat spreaders. Along with improving the cooling of the ram, the spreaders (from what I was also told by a marketing rep) will reduce EMI since it shields the ram, but I don't have any quantitative proof of that.

The kit is rated at PC2-6400, which works out to 800MHz. The ram timings are a little high, 5-5-5-12, and as many enthusiasts know, tighter timings normally result in better performance. However, as memory speeds increase, it is extremely difficult to maintain stability with such low timings and lately we've noticed that the timings seem to be having a lesser effect on performance as memory speeds increase.

All of the TWINX kits are tested in pairs and in a Dual Channel environment, which all of Intel's new chipsets (including offerings from VIA, NVIDIA and ATI) support. All the Pro Series XMS2 modules feature the same activity LEDs that makes this line of ram so popular. There are 24 LEDs present, and they light up as the ram is being used. They do look nice, and it's interesting to see how hard the ram is being pushed in a particular application, but they don't offer any actual troubleshooting use as the XPERT series do. I suppose if you turn on your PC, and they don't light up at all, you'll know you have a problem somewhere.


A will be used to test for reliability as well as stability during our overclocking tests. The card is quite expensive, but if you're testing a lot of ram, or you're a technician troubleshooting systems, this card is well worth the money.

How it works is that the R.S.T. Pro2 goes into a free PCI slot and after POST, it bypasses the OS completely, loading a proprietary OS and software package (embedded on the card itself). The card allows you to perform stress and performance benchmarks without the Operating System's memory footprint, memory resident programs, or drivers interfering with the memory installed. We'll provide a full review in the future, but that is the gist of it.

We proceeded with overclocking, and tested the ram via the memory tests on the R.S.T. Pro2 until we got a failure. At DDR2 800, the Koolance EXOS cooled ASUS P5WD2 Premium and P4 560 (3.6GHz) ES handled the TWIN2X2048 without any problems, so we're off to a good start since this is the rated speed.

Setting the ram speed at Auto, we then proceeded to crank up the FSB until we failed to POST. This occurred at 788MHz, though we were not able to get into Windows until we dropped down to 776MHz. We reinstalled the R.S.T. Pro2 card, and had some problems passing the memory tests at this speed. After bumping the memory voltage a bit higher (2.2v), the memory passed the test.

We should point out that at 776MHz, we were not able to reach anywhere near the ram's maximum rated speed of 800MHz. Since we do have an ES (Engineering Sample) Pentium 4, we fooled around a bit with the multiplier and FSB, and set the memory at a 1:2. With these settings, we settled on 914MHz as a maximum, stable overclock.

In terms of memory timings, the ram was pretty much dead set on 5-5-5-12 at all overclocked settings. At 800MHz, we were able to tweak the timings to 4-4-4-10, and pass the R.S.T. Pro2 tests.

Test Setup

ASUS P5WD2 Premium: Intel P4 560, Pentium 4 840 Extreme Edition, 2 x 1024MB Corsair TWIN2X PC6400 Pro, ATI X850 PE, 160GB Seagate SATA 7200rpm, Windows XP SP1.

The testing configurations will be as follows: Stock (800 @ 5-5-5-12) , OC = Overclocked (914 @ 5-5-5-12) and TW = Tweaked (800 @ 4-4-4-10).

The comparison memory will be Crucial's Ballistix 6400 (review forthcoming) run at stock speeds. The Crucial kit is a 1GB kit that I picked up recently and the point of including it here is to illustrate improvements (if there are any) from moving to 2GB from 1GB. We will also be altering CPUs during the tests depending on the application needs.

SiSoft Sandra 2005 Memory w/P4 560

Obviously, tweaking the memory timings have a positive affect on system performance, though not as much as sheer overclocking. There are minimal differences between the Crucial and Corsair parts, despite Corsair having a 1GB edge on the kit. These results are synthetic though, so let's look at real-world scenarios.

Battlefield 2 w/P4 560

Corsair recently published a document showing off the need for 2GB of ram in certain games. While we didn't match their numbers, there is a tangible difference moving up in ram for Battlefield 2. This game is simply ram hungry, so the more the merrier. How about another game?

Unreal Tournament 2004 Fastest w/P4 560

UT2004 doesn't seem to need the extra ram all that much, and benefits much more from faster ram. Luckily, the Corsair TWIN2X2048-6400 PRO overclocks quite well, and does a good job speeding up the framerates.


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