Black Edition Memory Profile for AMD Phenom

Has anyone had any experience with using Corsair memory with Black Edition Memory Profile (BEMP) with AMD Phenom for overclocking? I have purchased 8GB of 1600MHz DDR3 (CMD4GX3M2B1600C8), and would like to know what other users thought of the product.

AMD Press Release: AMD Black Edition Memory Profile lets users create custom profiles that can easily overclock known DDR3 memory to quickly and easily achieve optimum high speed DDR3 performance.

Corsair Blog: Both AMD users and Intel users now have the option of buying memory with memory performance profiles. These are pretested settings for the memory that can be utilized to automatically configure high performance memory settings in a quick and easy manner. AMD calls their method BEMP or Black Edition Memory Profiles. Intel’s version is XMP, or Extreme Memory Profiles. In some instances due to motherboard, memory controller, or BIOS limitations these performance profiles may not work correctly when all memory slots are loaded. In these cases, users will need to configure their memory settings manually.

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I have read some previous threads on about BEMP, but it is not clear if anyone has actually used it :confused:

BEMP or XMP profiles are only guaranteed when 1 kit is used, not 2 kits, especially on a Phenom CPU. rarely do i see a Phenom CPU operate at 1600 with 2 kits installed.

CMD8GX3M4A1333C7 or CMX8GX3M4B1333C9 are the only 8 gig kits supported and thats only at 1333. the 1600 kits are 2 or 4 gig max at those speeds.

BEMP or XMP profiles are only guaranteed when 1 kit is used, not 2 kits, especially on a Phenom CPU.

This seems counter intuative, because I would have thought that a 4 core Phenom and 4 modules (2 kits) of 2GB DD3 was a match made in heaven. Why does BEMP only work with two modules and not all four?

You are probably right that memory is not dedicated to a specific core, and appologies for assuming that it was.

What I meant to say that AMD Phenom CPU's support DDR3 dual channel memory, and each channel supports two DIMM's.

So who says that BEMP or XMP profiles are only guaranteed when 1 kit is used? I have not read anything about this limitation, so is this a guess or is this statement documented somewhere?

Overclocking

If you take a look at a current motherboard with overclocking options, you may see some specifications similar to this:

 4 X 240-pin DIMM sockets supporting a maximum memory capacity of 8GB

 Supports dual channel DDR2 1066/800/667/533 Un-buffered Non-ECC memory

Many users interpret these specifications too liberally. A motherboard that can overclock to a given speed with 2 modules cannot overclock to that same given speed with 4-up. Again, this is due to the increased electrical load on the north bridge or memory controller and the increased heat that accompanies it. So, many users are disappointed when they add memory and their overclocking capability is reduced. They tend to fault the memory for this limitation when it is actually a physical limitation of the memory controller.

A good analogy representing visualization of the above specifications is a passenger truck. Let‟s assume that the maximum hauling capacity of the truck is 8000 pounds representing 8gb of memory. The top speed of the truck is 106.6 mph representing a memory speed of DDR1066. However, this does not mean that the truck can haul 8000 pounds at 106.6mph. The physical limitations are similar for a memory controller as 8gb and 1066 are both tested maximums for this memory controller. When the memory controller speed is increased for overclocking, it simply cannot manage the same amount of memory at that overclocked speed for proper stable communication with the CPU.

This still does not make sense.

The specification of my DDR3 PC3-12800 can run at 1600Mhz using 1.6V. That is a lower voltage than DDR2 running at 1066 suing 2.1V, e.g. CMD4GX2M2A1066C5. Note that the voltage of DDR2 is over 25% higher than DDR3.

In theory, my DDR3 should be putting less stress on the memory controller, even if I were to overclock it by raising the voltage by 20%.

In your analogy, I am not running one truck, but two trucks as my CPU has Dual-channel architecture, so my trucks are carrying half the weight.

Not only that, my trucks use DDR3 which uses less voltage than DDR2, so the stress put on the memory controller should be less, not more.

I am not convinced the memory controller is the problem, as the evidence you have presented is insufficient, although you could be right nonetheless.

The frequency is the issue. The speed rating of 1600 MHz. is based on TWO modules not four for the reasons noted by Synthohol. Most Mobo user's manuals tell you that the memory will only run at speeds above 1333 MHz. in two slot, not four.

The more data the memory controller / HT must process the greater the heat and the more timing required to access all four memory slots/DIMMS without data corruption. If you lower the frequency to 1333 there is a better chance the four modules will work.

It's worth noting that AMD only rates the memory processing speed to 1333 MHz not 1600 MHz.

The frequency is the issue. The speed rating of 1600 MHz. is based on TWO modules not four for the reasons noted by Synthohol. .

I am still not understanding you and you are not providing details of the source of your information. As I said before, the Phenom CPU has dual memory architecture, each channel support two DIMM slots. If the all four DDR3 modules are run in ganged mode, then four modules are running as if they were two, in which case the bottleneck you have described goes away.

I think the problem with the truck analogy is that it is too trite. It does not explain the relationship between the CPU memory controller, the number and frequency of the DDR3 modules, and FSB speed of the motherboard. One of these is a bottleneck. What we need is a clear explanation as to why you can't overclock with four DDR3 modules other than "its a heat problem". I think the problem is that there is no shared understanding of how a PC specification works in practice and that there is no technical support to demonstrate that what you are saying is correct or not.

I am skill not understanding you and you are not providing details of the source of your information.

the link in my sig below is an official Corsair document. that is the source.

the hundreds of threads here that official Corsair tech support employees are citing that document and the official stance that listed speed is only guaranteed when 1 single kit is used per board.

with that said, there are a lucky handful of folks who have successfully mixed 2 separate kits and have been able to run them at listed speed but this is the exception, not the rule. that is why Corsair never suggests or recommends installing 2 or more kits on the same board together....EVER.

I have read the source, which says:

A motherboard that can overclock to a given speed with 2 modules cannot overclock to that same given speed with 4-up. Again, this is due to the increased electrical load on the north bridge or memory controller and the increased heat that accompanies it. So, many users are disappointed when they add memory and their overclocking capability is reduced. They tend to fault the memory for this limitation when it is actually a physical limitation of the memory controller

The problem with this statement is that is not addressing the points I made earlier: since my CPU has dual channel architecture, the load from a "4-Up"" configuration (i.e. four DDR3 modules) is split between two memory controllers. So going back to the truck analogy, I have two trucks pulling the same load (8GB of RAM) rather than just one, so 4 modules of RAM should not be problem.

One the one hand, this document suggests that 4 modules of 2GB RAM is a problem, but it does not suggest a common sense work around, such buying as 2 modules of x 4GB RAM, or running 4 modules in "ganged" mode. One the one hand, you seem certain that only two modules of RAM should be used:

the hundreds of threads here that official Corsair tech support employees are citing that document and the official stance that listed speed is only guaranteed when 1 single kit is used per board...that is why Corsair never suggests or recommends installing 2 or more kits on the same board together....EVER.

So it is still not clear what the right approach is: two modules or four modules. Another permutation is overclock just 2 of the 4 RAM modules. Either way, the official Corsair document is as clear as mud as to what is the real cause of the 4-module RAM bottleneck is.

I am not an engineer, but it seems to me that what is missing is what is the electrical load that one module of DDR3 puts on the memory controller. If we knew this information, then it would be clear what this document is saying. However, I am not even sure that electrical load is the problem at all, for there does not seem to be evidence to support this view one way or the other.

I am not trying to be smart here ('cos I am not), I am just saying that the existing documentation about this issue is not very satisfactory. Maybe the answer lies in the original JEDEC standard for DD3?

Corsair never suggests or recommends installing 2 or more kits on the same board together....EVER.

So how come Corsair recomends using 2 kits in their promotional material? Check out these links to official promotional material that clearly shows that Corsair highly recomends installing 2 kits on the same board:

* AN902: 8GB or More of System RAM—Doing More With More Memory

* AN902Corsair® Blog post from August 2009

The test system is 8GB of RAM using 2 x CMG4GX3M2A1600C6. Initially I thought these were two 4GB modules, but in fact it is 2 x 2 x 2GB modules (2 pairs of "matched modules", what ever that means).

It seems to me that Corsair does use 4GB, but just not overclock them.

To address the earlier question about BEMP or XMP and 2 modules vs 4 modules, the BEMP/XMP profile is specific to the KIT on which it is sold. For example, if you buy a 2 module KIT of memory, meaning 2 prematched and identical modules, then that profile is for 2 modules and not 4. If you buy 2 separate kits and try to run BEMP/XMP, it may or may not work as you are exceeding the tested specification.

However, if you buy a 4 module KIT that has BEMP or XMP, that means we have tested it to be stable with 4 modules. Of course, this is a moot point with BEMP because, as I said above, AMD has pretty much abandoned support for it.

FYI, AN902 is simply a test and NOT an endorsement of mixing 2 unmatched kits of memory together. Gareth has to use 2 separate kits as there were no 4 module kits available at the time. 2 kits cannot be guaranteed to work together.