16 Replies Latest reply on Feb 16, 2016 5:45 PM by tomtalk24

    Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?

    misterz_de

      Hello,

       

      the AMD-FX-Processor (AM3+) is the successor of the Amd Athlon II / Phenom II (AM3).

       

      AMD was AFAIK early to the market with a quad-channel Memory-Interface for the Operton for the Interlagos-CPUs, introduced to the market in November 2011 (Intel Westmere in 2010).

       

      Intel then introduced Triple-/Quad-Channel-Memory to the Desktop-Market in January 2011 (Sandy Bridge).

       

      The AMD FX-Processor was introduced to the Market in November 2011 with up to 8 Cores and higher Clock-Speeds compared to the previous generation (Phenom). A revised Version of the FX-Processor was introduced to the market in Oktober 2012 (Vishera), in 2013 extremely high clocked Versions of the FX-Processors (up to 5 GHz) were released.

       

      The Quad-Channel-Memory-Interface was never introduced to the AMD-FX-Processor, even though it is technically available since 2011 for the Server-Variants.

       

      When I run an 8-Core-Processor, especially with very high clock-rates (4 GHz+), the thruput in many applications will be limited by the Memory-Interface (especially when all 8 Cores are used in parallel).

       

      AMD should have been aware, that AMD will not be competetive against Intel (as they offer Quad-Core-Memory-Interface) for their Desktop-Processors since 2011 (the introduction of Sandy-Bridge-Processor).

       

      So why was this never added to the AMD-FX-Processor?

       

      Makes no technical sense for me (and is one reason, why I will not buy an AMD-FX Processor).

       

      Regards,

       

      Felix

        • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
          t77chevy

          I'm sure that will be available with zen releasing this year , been running fx for years and while its an older chip , for gaming still easily pushes my quadfire 295x2 setup . building a new pc for latest tech , zen is the obvious answer

          • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
            techguy

            The reason why AMD did not deliver quad channel RAM CPU designs to the consumer market is because there is no value in it nor actual need for it. In a server where you have large volumes of RAM and multiple CPUs, then quad channel offers a technical advantage. Intel released a castrated server CPU to consumers because they didn't want to bother with a proper desktop model. Thus the mobo makers were forced to offer quad channel for the particular server CPUs Intel was selling to consumers. Testing shows there is no tangible system performance gains with quad channel RAM over dual channel RAM for typical desktop operations. To keep consumers happy however, AMD is forced to offer quad channel as some folks mistakenly believe it's some technical advancement for desktop use when in fact with a single CPU, it offers no tangible system performance gains because dual channel isn't a system bottleneck.

              • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                misterz_de

                I think the answer "no technical need for Desktop-Environments" is to simple.

                 

                With this argument, there is no need for a Core I7 (with Quad-Channel-Memory) for any Desktop or Gamer-PC.

                 

                The Problem (for AMD) is, that some Benchmarks and probably some High-End-Games too will benefit from this extra Memory-Bandwidth and will show higher Results. This higher Result will be used by Sales-Organisations to argue, that Intel is "better" than AMD.

                 

                When you look at the AMD 9590-CPU, it is a 8-Core Design (at least 8-Core in the Integer-Area) and the typical Memory-Bandwidth will not exceed 8 (or with Overclocking-Memory maybe 10) Gbyte/Second (with Dual-Channel-Memory)

                 

                My old Phenom II-Processor is able to transfer about 4 GB/Second Single-Core and about 6 GB/Second Dual-Core from DDR3-Memory. (Geekbench)

                 

                Looking at these numbers you will see, that 8-Cores of the AMD 9590 would be able to transfer at least 32 GB/Second from Memory (if the memory would be fast enough) - so for a Memory-Intensive-Benchmark the Memory will be a bottleneck and a Core I7-Extreme with Quad-Channel-Memory will be faster...

                 

                So my opinion is, that from a technical perspective and also from a marketing perspective - the AMD FX-Processor ist not very well designed for an 8-Core-Processor, Dual Channel DDR3 would probably be fast enough for 4  Cores, but IMHO not for 8 Cores...

                  • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                    techguy

                    You can conduct your own tests with real applications and see that dual channel RAM is not even remotely saturated on a desktop PC the majority of the time, meaning that quad channel RAM will show no tangible system performance gains. As a point of reference ~1600 MHz. RAM is all that is required in a CPU powered desktop PC to handle memory tasks without causing a system bottleneck. Again this has been proven through actual testing with real applications. When you increase the RAM frequency to 2133 MHz. or higher there are minute system gains vs. tangible system gains because the only difference between the 1600 MHz. RAM and the faster frequency RAM is the real time interval in micro seconds. If you were running a server where the dual channel RAM could be saturated a high percentage of the time due to high traffic and multiple CPUs, then quad RAM can offer some advantage but in a typical desktop PC where you hardly ever saturate the RAM for more than a couple of seconds, there simply are no tangible system performance gains.

                     

                    From a visual stand point quad channel RAM on a typical CPU powered desktop PC is like having a four lane highway with only two cars on it. Until you use up all of the space on the two lanes, the two empty lanes aren't needed and can't provide any significant difference in how fast the cars get to their destination.

                     

                    One thing to understand is that benchmarks especially RAM benchmarks do not show the actual system performance gains, they show the RAM's "potential" gains if the RAM was saturated 100% of the time. Since the RAM in a CPU powered desktop PC is rarely saturated for more than a few seconds at a time, RAM benchmarks show wildly inaccurate system performance gains vs. actual system performance gains running real applications. The goal naturally is to sell higher cost, higher frequency RAM when it doesn't deliver any tangible system gains.

                     

                    One AMD non-believer with an OC'd FX-8350 ran a video game that is memory intensive at 1600 MHz. and 2133 MHz. The peak difference in FPS was "3" FPS @ 34-36 FPS average. You can't even see a difference of "3" FPS at 34 FPS so while it might sound great to say the video was up to ~10% faster, in reality you could not tell the difference between the RAM running at 1600 MHz. and at 2133 MHz. The obvious reason why is because the dual channel RAM wasn't saturated most of the time and thus the only minute gains were from the real time difference in frequency in the RAM. Intel owners have found the same results in many different tests. When quad RAM was first released to desktop consumers by Intel many tests were done on the Intel CPUs and the results were the same, minute differences in system performance because the RAM is not saturated most of the time. When you're talking small percentage system gains in benches, it's obvious that quad channel and high frequency RAM is being over sold vs. it's actual performance benefits for desktop use. Running your own test with different frequency RAM may be useful. On many mobos you can also select between single or dual channel RAM operation. Try running some tests with single vs. dual channel RAM on your desktop PC.

                      • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                        misterz_de

                        Well, it is too easy to look at the MHz-Rating only, you will have to look at the Latency as well.

                         

                        And yes, there is a difference - beleive it or not - between Dual-Channel-Memory and Quad-Channel-Memory, look at this:

                         

                        Intel's Core i7-6700K 'Skylake' processor reviewed - The Tech Report - Page 4

                          • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                            qbtheslayer

                            Memory benchmarks...  yeah they push the memory to it's limit, but very little on a desktop PC actually does this.  Someone's reading comprehension needs a little work since that was already stated above.  Of course quad will offer more performance, but it's performance you will only ever see when using a benchmark that pushes that particular feature.  Don't get me wrong, I'll be all over that like white on rice, but at least I will know not to expect any noticeable increase in actual daily use/gaming.

                             

                            QB

                            • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                              techguy

                              Latency on DDR3 RAM of ~1600 MHz. and higher shows even less system improvement than the higher frequency does because DDR3 RAM running at ~1600 MHz. is not a system bottleneck. Latencies as well as frequencies above 1600 MHz. have been proven in real testing using real applications to NOT deliver any tangible system performance gains on CPU powered desktop PCs. This has been known and proven for years as DDR3 RAM of ~1600 MHz. effectively eliminated the system bottleneck that DDR and DDR2 created. Back when all we had was DDR or DDR2 then latency and frequency would show some small system improvements because DDR and DDR2 did not have the bandwidth to match the CPU's capability. Those days are long gone, thankfully.

                               

                              The link you show is again benchmark testing of specific text block sizes. It is not realistic because your PC constantly processes different length data blocks. The test shows theoretical gains or "potential" gains assuming the RAM is saturated 100% of the time but it is not saturated in a normal CPU powered desktop PC. If dual channel RAM was saturated then you would see significant gains in performance with quad channel. And in server use with multiple CPUs and large RAM banks, with high data loads you will see an improvement in system performance. With low data loads it's again like a desktop CPU powered system with no bottleneck and thus no tangible system performance gains with quad channel vs. dual channel

                                • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                                  misterz_de

                                  You might be right for typical Office-PC-Usage, but with the same argument you can question an 8-core-CPU for Desktop-Computers, too.

                                   

                                  Normal Applications like Windows 7/8/10, Office XY or Internet-Browsing, E-Mail and even most Computer-Games will not benefit form an 8-Core-CPU at all. In such simple Applications a 2-Core-CPU will probably be faster than an 8-Core-CPU, just becuase 2-Core-CPUs are usually clocked a liittle bit higher than 8-Core-CPUs....

                                    • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                                      techguy

                                      You're going sideways on me now with trying to compare apples to oranges...

                                       

                                      FYI- A dual core CPU of the same design as an 8-core CPU does not process more info. than an 8 core CPU in a given time span even if the dual core had a slightly higher frequency. How well an X86 CPU with more than four cores performs is deeply dependent on how well the software and O/S are written. If you use a screen applet that allows you to view the core loads real time you'll see that when given sufficient load, all eight cores can show heavy processing loads. Obviously if the CPU isn't asked to process a large volume of data all at once then only a few cores are heavily loaded.

                                       

                                      The bottom line is when running real applications on a single CPU powered desktop PC, dual channel RAM is not a system bottleneck nor will quad channel show a tangible system performance boost with current X86 CPU designs. The RAM frequency and latencies also make no tangible system performance improvement in a single X86 CPU powered desktop PC because RAM running at ~1600 MHz. or higher is not a system bottleneck. By running real test with real applications one can see this for themselves. Hopefully down the road a few years, it would be nice to have desktop CPUs that can actually benefit from quad channel RAM.

                                        • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                                          misterz_de

                                          Your answers are too simple. What is your background? You can´t just talk about the RAM-Frequency in MHz without looking at the latency.

                                           

                                          That´s too simple.

                                           

                                          The thing is, AMD is not very competetive at the moment, look at the market share. Im just talking about what other companies have to offer (Intel i.e. Quad-Channel-Memory, High-clocked Dual-Cores, etc.).

                                           

                                          And in the Server Market IBM has to offer 8-channel-memory, etc.

                                           

                                          AMD has nothing to offer in this area at the moment. Obviousliy some customers see things different than you. You can always say "you will not notice the performance gain, etc.", problem is, that enthusiasts will always prefer CPUs with more / better features / higher clock-rates, etc.

                                           

                                          I hope AMD will change with ZEN, otherwise I see no future for AMD at all in the high-end / server-market. And that´s the market, where you can really make money.

                                            • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                                              techguy

                                              Apparently you didn't read or understand my comment above about latency showing even LESS system gains than higher RAM frequency changes.

                                               

                                              All of what I have posted here is supported by actual user testing with real apps. If you understand that DDR3 RAM running at ~1600 MHz is NOT a system bottleneck on a single X86 powered desktop PC, then you should understand that increased frequency or reduced latency only delivers the micro second difference in RAM frequency or clock cycles in latency. As the RAM frequency increases the real time of one clock cycle decreases but the difference between 1600 MHz. RAM and 2133 MHz. RAM is insignificant when the RAM is not saturated for any length of time. Quad channel will NOT provide any tangible system performance over dual channel RAM unless the data load is sufficient that dual channel becomes a bottleneck. This type of data load isn't typically experienced in a normal single X86 CPU powered desktop but it IS experienced in a multi-CPU server with lots of RAM and data processing. That is why quad channel was developed for servers and not for desktop PCs where dual channel isn't even close to being saturated in most applications. If you do the testing properly you can see this for yourself.

                                               

                                              Now as far as AMD not being competitive in the desktop CPU market, they are well aware of this reality. That is why three years ago they embarked on restructuring AMD and developing a complete new, competitive CPU architecture that will allow AMD products to equal or exceed Intel X86 products. AMD will deliver the first Zen based products this year based on the new CPU architecture which reportedly will offer quad channel support. As noted previously this is to appease those who falsely believe that quad channel RAM offers some performance advantage on a desktop PC even when testing with real apps shows that it doesn't provide any tangible system performance gain. Since AMD needs quad channel for their enterprise CPUs it's simple enough to leave it in the consumer Zen based desktop CPUs.

                                               

                                              One of AMDs strong suites at the moment is their excellent performing APUs. The superior performance is why AMD has contracts to supply the three major console makers. With Zen coming to market this year, AMD's entire product portfolio will be up to date and state of the art and fully competitive with any X86 products from Intel. Zen will be used extensively in enterprise as it was designed from the ground up for this purpose. Reports of 32 Zen core enterprise CPUs and 16 Zen core enterprise APUs have already been "leaked" to the media. AMD needs to continue to execute and keep their product fresh and relevant if they expect to enjoy good sales and brand loyalty.

                                                • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                                                  misterz_de

                                                  Hello,

                                                   

                                                  I understand your arguments, but I am a IT-Professional. The primary target of the current AMD-Products is probably the Gaming- / Home-User-Market where People look for Features and big Numbers, etc., but probably not for real-performance / suitable technical design.

                                                   

                                                  I understand, that some People like the design of current Processors (FM2, AM1, etc.), but as I said - for me as an IT-Professional this is not a design that I would buy - not even for home use.

                                                   

                                                  If AMD no longer wants to target "IT-Professional" or "Business Users" with there products, this is O.K.

                                                   

                                                  The problem for AMD might be, that there is not enough margin to make profit with this kind of products...

                                                   

                                                  Regards,

                                                   

                                                  Felix

                                • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                                  ammad1991

                                  I have Question That will amd make power processor better then Amd fx and i also want to know that what is the current gen of cpus of amd

                                    • Re: Why is there no Quad-Channel DDR3-Memory-Interface in the AMD FX-Processors?
                                      techguy

                                      The current gen of discrete desktop CPUs are the FX 83xx and FX-9xxx series CPUs. The FX-9xxx series are 220w overclocked models that require a special mobo that can properly power these CPUs. The FX-9xxx series CPUs are factory overclocked 125w FX-8xxx models. A quality mobo is also required for the 8-core FX-8xxx series CPUs. Always check your mobo makers website before purchase to insure that your favorite mobo supports the specific AMD FX model CPU you desire to use.

                                       

                                      The next gen of AMD desktop processors will arrive in Q4 of '16. These are part of the brand new Zen family of AMD processors. The desktop consumer model CPUs are named "Summit Ridge". They will have up to 40% faster IPC than the current Excavator core AMD processors used in the latest Athlon and APU models. The Excavator core is faster than the Vishera core used in the current FX desktop CPUs so the Zen based products will provide a substantial increase in system performance.