G.Skill F2 6400 CL4D-4GBPI-B Review

ccokeman - 2008-10-05 13:34:39 in Memory
Category: Memory
Reviewed by: ccokeman   
Reviewed on: October 15, 2008
Price: $69.99


Two of the biggest concerns with memory modules are voltage and getting rid of the associated heat that an increase in voltage brings. There are not only those issues, but enthusiasts have been asking for modules that have tighter latencies to increase the performance of their systems. Memory manufacturers have been happy to oblige to this demand but have had to increase the voltages on even DDR2 800MHz modules to keep up with this demand. I have one set that requires 2.3 volts to run 3-4-3-8 at DDR2 800. There comes that heat that has to be controlled and dissipated to keep the modules alive. How many times have you marveled at an amazing overclock on a set of memory modules and then seen the obligatory system shot that shows a big old 120mm fan blowing air over the modules to keep them cool and stable? For me, more times than I can count! In fact I am part of that club. Sadly! Well G.Skill has just released a set of modules that solve three issues. Tight latencies at DDR2 800MHz speeds, with low voltage and a large cooling solution for improved cooling efficiency. The G.Skill Black PI PC 6400 2x2GB kit has latencies of 4-4-4-12 at a low 1.9 volts versus 2.1 or greater volts to reach this level. The PI thermal management solution is said to offer a reduction in operating temperature up to 20 percent lower than traditional memory heatsinks. How will the thermal solution help with the overclocking of these modules? Will additional volts heat them up? How far can they be pushed? All questions to be answered. Let's see what the latest from G.Skill has to offer the enthusiast!

Closer Look:

The PI series module come in a solid black box with just the symbol for PI on the front of the box. Kind of reminiscent of the Metallica Black album. Simple and straight to the point. The rear has a sticker with the part number of the modules, the G.Skill name and slogan, as well as the company contact information. The package has a flip-open front cover that has a window to view the modules on one side as well as a presentation on the benifits of the attached PI heat spreaders.




Once out of the box, the modules are encased in a plastic clam-shell that prevents any movement in transit. Included with the modules are a quick start guide and several stickers for those collectors out there.



The G.Skill F2 6400 CL4D-4GBPI-B set of modules are rated for use at a low 1.9 volts at the low latencies of 4-4-4-12. A significant reduction in the voltage requirement from the normal 2.1 volts normally needed. G.Skill is also using an over-sized heatsink to keep these modules cool and stable under any condition. The heatspreaders appear to be securely mounted. Each half of the heatsink assembly crosses over the other in an interlocking design that is sure to promote the dissipation of the heat generated by the modules.




Now let's see what these modules are capable of.



Main Board
System Type
M/B Chipset

Intel X48,
Intel P45,
Intel X38,
Intel P35,
Intel 965,
nVidia n6xx I (For Intel series),
nVidia nForce 5 series (590SLI, 570 Ultra. Others For AM2) 

4GB (2GB x 2) 
DDR2 800 (PC2 6400) 
1.8~1.9 volts 
6 Layers 
240-pin DIMM 








All information on this page courtesy of G.Skill@http://newgskill.web-bi.net/bbs/view.php?id=g_ddr2&page=1&sn1=&divpage=1&sn=off&ss=on&sc=on&select_arrange=headnum&desc=asc&no=126


The best way to verify whether one set of memory modules is better than another, is to run a series of benchmarks and put down some basic comparison data. When all things are equal, and the only variable is the module being tested, the results are a great way to compare performance. In order to eliminate the variables, the only settings that will be manipulated are the memory timings, and voltages when overclocking. The comparison modules will be run at the manufacturer specified timings and voltages at 800MHz, the common DDR2 speed. Since this is OCC we can't just let the performance at stock speeds tell the whole story. Stock speeds just won't do for us! After the stock speed comparisons the modules will be pushed as far as they will go to see just what kind of performance can be gained from the modules when overclocked.

Testing Setup:

Comparison Modules:



CPU-Z: This application shows us the settings that we have chosen in the BIOS. Items shown in this application include CPU speed and bus settings, motherboard manufacturer, BIOS revisions, memory timings, and SPD chip information.


Task Manager: We use this utility to show physical memory, kernel memory, page file usage, and processor usage (%).



Overclocked settings:

Considering the fact that the modules run at Cas 4 DDR2 800 (400 FSB) at lower than the specified 1.9 volts with no issues, the overclocking potential looked promising. Getting to 900MHz (450FSB) was just a matter of adjusting the voltage to the voltage specified by G.Skill to run the modules at the stock speeds. Looking better! Pushing to 1000MHz (500FSB) required a couple of things from these modules. First was an increase in the vDimm to 1.95 volts and adjusting the Cas latency to 5 was needed to even boot. Still looking good at under 2.0 volts. Now pushing up to 1066MHz (533FSB) was where the drama started for me. I adjusted the timings to 5-5-5-12 to see if the modules would allow a boot at 2.0 volts! No go! 2.1 volts was still a no go, so I had to push 2.2 volts for 1066MHz to become a reality. Pushing higher even with 2.3 volts did not yield any additional increase in memory speed. So with my max speed set at 1066MHz at 2.2 volts, I went for the timings to see if they could be coaxed down any further. 5-5-4-12 at 1066MHz (533FSB) was the best I was able to achieve with the G.Skill Black PI modules. Some things you have to remember here is that this is a 4 gigabyte memory kit that runs Cas 4 at 1.8 volts and retails for 70 dollars. Just because a set of modules has a big heatspreader does not mean that the heatsink is effective. The heatsink on the G.Skill PI modules has a unique heatspreader that seems to effectively remove the heat generated by the modules. They were never hot to the touch even during the 2.3 volt testing phase. While the modules did not give the largest overclock on a set of 4GHz modules for me, they did do an admirable job of making it to 1066MHZ with decent timings and great performance.


The benchmarks that will be used in this review include the following programs:




PCMark Vantage: With this benchmark, I will be running the system suite as well as the memory test suite. The measure for the system suite will be the total score. The measure for memory performance is the total memory score.















SiSoftware Sandra XII: In this program, I will be doing the following benchmarks: Cache and Memory, Memory Bandwidth and Memory Latency.  Higher is better in all tests, except for Memory Latency, where lower is better.






We have a mixed bag on the results in these benchmarks. In the PCMark Vantage memory testing, the G.Skill modules are out-performed by the Mushkin and Geil modules, yet the suite score for the G.Skill modules are only outperformed by the Mushkin modules. In the latency testing, the G.Skill modules perform better than all of the comparison modules. The memory bandwidth scores mirror the latency results and the G.Skill provide more memory bandwidth at the DDR2 800 level.




Company of Heroes is a real time strategy game set during World War II. The object is to occupy and control the ground you capture, while forcing the opponents to capitulate. We will use the in-game performance test to measure the performance of the system.


The settings used in this test are listed below:














Higher is Better


The G.Skill PI series memory allowed a higher average FPS in two out of the four resolutions. In one test, there was a tie score.



The Black Pi series of modules do what they are designed to do. The voltage specified on the modules for Cas 4 operation is 1.9 volts. At the default speeds, the modules ran at the DDR2 Jedec spec of 1.8 volts. This is much better than the alternative, needing 2.0 to 2.1 volts to run at an 800MHz speed. With such a low voltage requirement, one has to wonder about the need for such an elaborate looking heatspreader. Running at stock speeds, the modules felt no warmer than they did when sitting in the package. When pushed to the limit with 2.25 volts on them, the modules were just barely warmer to the touch. It looks as though the claim of reducing module temperatures (Heatspreader) by 20% over a traditional design, may hold some truth. When it came to overclocking the PI series modules, I was only able to pull an additional 133MHz out of the modules by increasing the Cas latency to 5. This took an increase in voltage to 2.2 volts to get them stable. To go to DDR2 900MHz, all it took was an increase in voltage to the specified 1.9 volts at Cas 4. Pretty decent when you consider the voltage needed to do this. Right now DRAM prices are ridiculously low and have been in a downward trend for quite a while. If you are not going to be running a DDR3 based system for the foreseeable future, then spending $70 dollars to upgrade to four gigabytes of system memory would be a wise decision. Especially considering Vista users can benefit from the additional responsiveness the additional system memory brings. A good looking and effective thermal solution, tight timings, decent overclocking, low price, excellent performance, low voltage requirement and a lifetime warranty makes the G.Skill Black PI 4 gigabyte set of modules a good choice for your next build, or as an upgrade from a 2 gigabyte set. With all the pluses, you can't go wrong.