DDR650? - No Problem! Two Memory Kits from G.SKILL in Our Lab

We would like to introduce to you memory solutions from the Taiwanese G.SKILL company targeted for extreme overclockers. Two memory kits, DDR600 and DDR566, are going through detailed testing in our lab today. You’ve always wanted to get excellent characteristics for a modest price. Now you can go for it with G.SKILL memory!

by Kirill
08/20/2005 | 08:22 AM

Even after the release of high-frequency DDR2 modules (up to DDR2-1066) overclockers are still interested in ordinary DDR SDRAM, especially when it comes to the AMD64 platform. Recently the Taiwan-based G.Skill introduced a new DDR600 (PC4800) model with most impressive characteristics in their FR series and a midrange DDR566 (PC4400) model with heat-spreaders in the FC series.


The products to be reviewed today are targeted at extreme overclockers. The senior model is based on Samsung’s TCCD chips and is thus expected to be very good at overclocking. As for the PC4400 kit, it seems to be a lucky combination of good characteristics and modest price.

About the Company

G.Skill is not perhaps a well-known name among the common public, but is a respectable brand in the overclocking community. G.Skill International Enterprise Co., Ltd. with headquarters in Taipei, Taiwan, was founded in 1989 by a group of enthusiasts. The company focuses on manufacturing PC memory as well as flash cards of Secure Digital, MultiMedia Card and xD Picture Card formats and USB 2.0 flash drives with capacities up to 1GB. As a maker of top-end overclocker-targeted memory G.Skill debuted only in 2003. So, the company has not been long on the markets of Europe and America, but has already won universal recognition.

The company’s overclocker-friendly DDR Extreme series currently includes over 15 products ranging from DDR400 to DDR600 with varying timings. It is in this series that G.Skill offers memory modules with exceptional characteristics and fine overclockability. All memory modules from G.SKILL come with a lifetime warranty and pass through factory tests to guarantee their best quality, performance and compatibility.

Besides the top-end DDR Extreme series, G.Skill offers:

Top-end DDR modules are the flagship product from G.SKILL, though. So, let’s get to know them closer.




Package and Accessories

All modules from G.Skill are packaged alike, into a sealed plastic envelope with a colorful insert inside.

You can learn some marketing info and read a short manual at the back side of the package. The G.Skill F1-4800DSU2-1GBFR memory kit consists of two PC4800 (DDR600) modules, 512MB each.

A sticker on the package tells you the capacity of the kit and another one is more informative, telling you the rating, timings and name of the modules. The kit doesn’t include any accessories.

The G.Skill F1-4400DSU2-1GBFC kit also consists of two 512MB modules, but rated as PC4400 (DDR566).

The package is the same as with the first kit.

Closer Look

Let’s start with the senior model. It is hard to think of a simpler design for a memory module – this product looks just like ordinary DIMMs of low-end DDR SDRAM. This heat-spreader-less design is typical for a majority of sticks from G.Skill and is quite acceptable both for economical reasons and from the end-user’s viewpoint. An overclocker who’s going to use these modules under extreme conditions with an increased voltage will anyway have to take special measures to cool this memory and will most likely prefer third-party solutions. And for the ordinary, non-extreme use additional heat-spreaders aren’t actually necessary.

Without them, the memory chips are in full view. Unlike with the DDR ZX series where there was G.Skill’s own marking, the F1-4800DSU2-1GBFR modules betray the origin of their chips at once. Yes, these are Samsung’s TCCD chips, so valued by overclockers for their excellent overclockability and configuration flexibility. There are eight chips on each side of the PCB, giving you a total of 512 megabytes. Judging by the modules’ behavior, G.Skill additionally culls the best chips since even Samsung’s TCCD don’t generally support such operational modes as G.Skill declares.

A PCB of the BrainPower B6U808 type is employed for all DDR products from G.Skill. Statistical data suggest that modules based on such PCBs generally have a higher potential than those based on JEDEC’s reference PCBs. So, this is yet another plus for G.Skill.

The sticker on the face side of the product tells you all the necessary information about its characteristics: F1-4800DSU2-1GBFR 512 MB DDR PC4800 CL 2.5 448 2T 2.7-2.9V

We want to note one change in G.Skill’s way of marking their modules. Earlier models with PC4400 and PC4800 ratings used to have a double marking: besides their “native” operational mode, they were marked as DDR400 2-5-2-2 (TCCD chips have no problems working like that). The FR and FC series do not use this double naming anymore, keeping only their main marking.

The second kit from G.Skill is remarkable for its exterior in the first place. The modules are equipped with heat-spreaders as you can see below.

These are unaltered heat-spreaders of the typical design, the same as Kingston, Transcend, Crucial and many other manufacturers use: two anodized aluminum bars connected with two chromium-plated metal clamps.

G.Skill’s logotype and web address can be seen at the center of the heat-spreader. The whole looks like they have given little thought to the design…

Unlike original heat-spreaders from Corsair and GeIL, these can be removed quite simply. To avoid people doing that, G.Skill put a sticker on one of the heat-spreader’s clamps. If the sticker is damaged, the warranty becomes void (there’s a special warning about that on the package). Well, if you do everything carefully, you can release the clamp without tearing the sticker up.

By the way, the above-mentioned sticker contains such information about the module as its name, type, capacity and timings: F1-4400DSU2-1GBFC 512 MB DDR PC4400 CL 2.5 448 2T 2.7-2.9V

We still removed the heat-spreader to see what chips were there, but you should not do that unless you want to lose your warranty!

We’ve got TCC5 chips here, i.e. Samsung’s less expensive circuitry than the top-end TCCD. Like the first kit, the module uses a PCB of the BrainPower B6U808 type.

Now that we’ve looked both kits over, we can proceed to our tests.

Testbed Configuration


We test modern memory modules, especially overclocker-friendly ones, only in the dual-channel mode since all top-end platforms today support dual-channel memory access. The overclocking potential is somewhat reduced in this mode, so people who use Athlon 64 for Socket 754 or Dothan processors and older platforms like Intel’s 845PE/848P can add at least 10 megahertz to the numbers from the tests, especially at relaxed timings.

Unlike with graphics cards, memory modules of one type generally differ little in their overclockability, so the results quite precisely indicate the overclocking potential of the modules.

We tested the memory in four different modes: with minimal (2-5-2-2-1T), average (2-6-3-3-1T), maximum (2.5-8-3-3-1T) and default (2.5-8-4-4-2T) timings. We performed our tests at 3.0B memory voltage (this is the limit of the employed mainboard in its unmodded state). All the performance-related BIOS settings were set to their highest-performance values.

First let’s take a look at the SPD information from both memory kits:

Both kits have competently written parameters. The lack of extra-low timings at DDR400 frequency guarantees compatibility with a majority of mainboards (sometimes you may run into trouble with low-latency modules that have something like 2-5-2-2 written into their SPD). The second column on the screenshot contains parameters of DDR566 (PC4400) mode with most sparing timings.

The only strange thing is that the SPD chip of the F1-4800DSU2-1GBFR kit contains the PC4400 parameters, including the module type. On the other hand, we have seen even more ingeniously written SPD which doesn’t affect the performance of the module in real situations. And again, keeping the default timings high ensures better compatibility with some mainboards.

Note that the CAS Latency parameter is set to 2.5, as in the specification. The fact is Samsung’s TCCD chips do not like CAS = 3! Setting this parameter to 3 should theoretically lead to better overclockability than with 2.5 CAS at the expense of a certain performance hit at the same frequency. But this is only theoretically true. In practice, overclockability of TCCD chips worsens in this case, sometimes quite much…

Let’s first check the senior model.

The declared DDR600 is a very serious frequency, rarely achievable by DDR modules without your taking special measures. And still the F1-4800DSU2-1GBFR kit really worked at this frequency with the specified timings. The voltage was 2.7V, i.e. the lowest specified (2.7-2.9V). This is impressive already. From this starting point we enthusiastically got to squeezing the juices from G.Skill’s top product.

Our further experiments (at 3.0V) produced the following results:

Our tests prove that these modules easily reach an astonishing frequency of DDR650 (or PC5200) at a modest voltage of 3.0V and with 2.5-8-4-4-2T timings. That’s an outstanding performance even for TCCD-based chips!

When we selected the minimum timings (2-5-2-2-1T), the memory was stable up to DDR450. This is somewhat worse than Winbond’s classic BH-5 chips can do (DDR466 and higher under the same conditions). But those famous BH-5 (long out of production and unavailable today) couldn’t even dream of the configuration flexibility that Samsung’s TCCD chips offer.

Having such an outstanding memory kit on our hands, we couldn’t help try it at extreme overclocking. We performed a simple volt modification to increase the DIMM voltage to 3.3V.

As you can see, the G.Skill kit behaves much like BH-5 chips that usually overclock to 240-250MHz at the lowest timings and at 3.3V. The most interesting results, however, are about 2.5-8-3-3-1T timings. The mainboard we use is known to dislike 1T at memory frequencies above 275MHz. But the G.Skill F1-4800DSU2-1GBFR kit seems to make an exception: the modules were stable at DDR610 frequency with 1T Command Rate. Besides that, we could lift the memory frequency up by 5MHz more, to 310 (DDR620) MHz, by choosing 2.5-8-4-4 timings (with Command Rate = 1T). As for overclocking with Command Rate = 2T, the results are clearly limited by the potential of our sample of the ASUS A8N-SLI Premium mainboard: the memory couldn’t pass our tests at DDR666.

Having played enough with this exceptional memory, we then took DDR566 modules from the G.Skill F1-4400DSU2-1GBFC kit into our hands. These modules were absolutely stable in their rated mode, i.e. as DDR566 with 2.5-8-4-4-2T timings and 2.7V voltage.

Next we increased the voltage to 3.0V (we didn’t check this kit with volt-modding) and found the following frequencies to be the maximum stable ones:

This is smaller than with G.Skill’s F1-4800DSU2-1GBFR and, unlike with the top product, is quite typical for chips from Samsung. On the other hand, the kits differ rather much in price, making the G.Skill F1-4400DSU2-1GBFC kit a much more affordable product.


The Athlon 64 platform is highly sensitive to the memory subsystem latency. The memory controller integrated into the CPU doesn’t act as a bottleneck and this leads to a dramatic growth of the overall performance of the system as soon as the timings are lowered. A difference between 2-5-2-2 and 3-8-4-4 in the DDR400 mode amounts to 20% in average in real applications and is even bigger in some benchmarks.

So the notion that “modules with minimal timings are optimal for the Athlon 64” is still quite persuasive and is in fact true in most situations. But today we have an untypical case: few companies can offer DDR SDRAM capable of working at frequencies that high! We carried out a short test of the memory subsystem using the G.Skill F1-4800DSU2-1GBFR kit in default and extreme modes (the above-indicated frequencies at Vddr = 3.0V and 3.3V). To account for measurement errors we rounded the numbers off to 50KB/s.

The results were not quite what we had expected. Yes, the low latencies at DDR450 push the performance of the memory subsystem to the level of DDR650 with “slack” timings, but DDR400 with the extreme timings is considerably slower than DDR600 at the default timings. Yet this is all quite predictable. What’s much more exciting is the memory performance in the 2.5-8-3-3-1T @ DDR600 mode. It’s the first time we see a memory speed of nearly 9000KB/s in Sandra Memory Benchmark!

This outstanding performance is due to a single BIOS parameter: DRAM Command Rate set to 1T instead of 2T as is the default for DDR600. Alas, the beautiful number (DDR600) is not achievable in this case at 3.0V voltage (you have to increase it by 0.3V more), but we’d anyway like to compare the effect of DRAM Command Rate = 1 to an injection of nitro into a car engine. :)


Our tests have proved that the fine reputation G.Skill enjoys in the overclocking community is well-earned.

The G.Skill F1-4800DSU2-1GBFR kit impressed us with its ability to keep stable at DDR650 frequency without our taking any special stability-improving measures and also with its ability to work close to DDR600 with 2.5-8-3-3-1T timings without mainboard modification. And of course, this kit offers all the advantages of TCCD-based modules, including their ability to substitute BH-5 chips at the lowest timings.



G.SKILL modules are less widespread in the market than modules from the leading companies like Corsair or Kingston, but you shouldn’t think twice if you spot them in a shop. Just grab them!

The junior model, G.SKILL F1-4400DSU2-1GBFС, doesn’t have the magic properties of the above-mentioned product. But it costs much less.



This kit works well and deserves attention from people who are looking for high-quality memory for a midrange computer.