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 DDR3 Memory Frequency Guide

Article Number: CPU-DDR3


Motherboard BIOS and Windows® based memory testing tools report that the installed DDR3 memory is running at a lower speed than expected.

In the following guide, we will discuss what determines your systems standard memory speed and how to explore what the maximum speed of each memory component is.

Memory speed overview

By default, your computer system will use the safest speed settings that it can automatically detect from within the memory components. This speed will be limited by your slowest component.  Please note that some Windows based tools will report your memory speed to be half of the speed in a DDR memory configuration, e.g. Tool reports memory speed of 667MHz which equates to a DDR memory speed of 1333MHz.

The memory components consist of

Memory Controller 

  1. The memory controller
    1. The memory controller is integrated into the AMD processor. The maximum speed supported varies by processor family and is also limited by the amount of memory slots used.  



Depending on your selected motherboard and memory, the published speeds and configurations above may be exceeded, which will result in running your AMD processor outside of AMD published specifications. See note.  For details, please see the guidance below and contact your motherboard manufacture or memory supplier. 
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Memory Modules

  1. Factors determining memory speed​
    1. When installing modules of memory of differing speed grades or brand, the memory will always run at the speed of the slowest module installed.
    2. Some memory modules have two speed grades, a tested maximum speed and a standard speed. In automatic selection mode, the standard speed will always be used.
    3. The amount of populated memory slots can affect the achievable final memory running speed.
    4. Memory design in Single or Dual rank can effect memory speed
      1. Most memory should be clearly identified if it is dual rank memory and if not identified, it is usually single rank memory.
      2. Dual rank memory will run slower than a Single Rank memory of equal quality, as it requires an extra step when addressing memory locations.  

Identifying your memory modules and their specifications

 Check the labels on the memory to identify the make and model number of your memory - 



The two pictures above show a single piece of memory, this is also referred to as a DIMM (Dual Inline Memory Module) and the second picture shows a close up of the memory DIMM label.

The label shows details such as the memory manufacturer and the part number which usually incorporates some of the memory specifications. On our example here, the memory part number is KHX2133C9AD3X2K2/4GX.

Once you have the memory part number, you can download specifications from the memory manufactures website.  In the description of our example memory we can see that this memory has a tested and published speed of 2133. The standard speed which the BIOS will detect from reading the memory module is 1333. In the example below,  the Serial Presence Detect (SPD) programmed speed is 1333.



In automatic selection mode the BIOS would therefore run our example memory at 1333. In order to achieve the tested speed of 2133, you would need to manually adjust the memory speed settings. However, this will also need to be supported by the motherboard.

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Motherboard & BIOS​​

Motherboard manufactures determine their own limitations for their motherboard design which may exceed the AMD memory controller specifications.  These will require manual set-up. The required settings and limitations are usually published in the form of a Qualified Vendor List (QVL), and are available from the motherboard manufacturer website.  If the settings and limitations are not published,  contact the motherboard  manufacturer directly. 

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How to determine the maximum achievable memory speed based on the motherboard manufactures published Qualified Vendor List.

In order to achieve your memory modules rated speed, you will have to ensure they are included on the motherboard QVL list. The QVL should detail the required timing, voltage and maximum amount of supported modules for the desired speed.

Example QVL list below for 1866 speed memory on an Asus Crosshair V Formula motherboard


If we take the OCZ3G1866LV4GK as an example, we will need to set the memory timings to 10-10-10 and the memory voltage to 1.65 and we will be limited to a maximum of 2 x modules e.g. 8GB.  Using more modules may require us to reduce the speed.

If data is missing or the details provide by the motherboard manufactures do not contain voltage, timing settings and number of memory slots supported, you will have to contact the motherboard manufacturer for more details. 

Please Note:
AMD processors are intended to be operated only within their associated specifications and factory settings. Operating your AMD processor outside of specification or in excess of factory settings, including but not limited to overclocking, may damage your processor and/or lead to other problems, including but not limited to, damage to your system components (including your motherboard and components thereon (e.g. memory)), system instabilities (e.g. data loss and corrupted images), shortened processor, system component and/or system life, and in extreme cases, total system failure. AMD does not provide support or service for issues or damages related to use of an AMD processor outside of processor specifications or in excess of factory settings. You may also not receive support or service from your system manufacturer.