Question: What is Intel Flex Memory technology?

Read our answer below:

Intel Flex Memory technology is the official name given by Intel to its own brand of memory controllers supporting what is known as symmetrical and asymmetrical dual channel mode. The memory controller in older Intel based laptops is found within the northbridge chipset (up to circa 2009) while in modern Intel based laptops it is found within the processor die, in other words it is an integral part of the system processor.


Intel launched its Flex Memory technology together with its unveling of DDR2 memory compliant laptop mobile chipsets back in 2004, namely the Intel 910 and Intel 915 family of chipsets. It has been supported by Intel memory controllers since this date.


In order to recap, dual channel mode is the memory operating mode that is activated in compatible systems when two identical SODIMM laptop memory modules (in the case of laptops) are installed. By identical one understands the following:


  • Capacity - both SODIMM memory modules need to feature the same capacity (i.e. 2x 512MB, 2x 2GB and so forth)
  • Specification - both SODIMM memory modules will need to have identical SPD data encoded into them, the best means to achieving this is to always install the same model of modules from any one manufacturer

While it is ideal that the following conditions are also identical between the two SODIMM memory modules, this isn't necessary:


  • Brand - Intel Flex Memory technology does not pay attention to the brand of each SODIMM memory module, however installing the same brand is a sure set way to easily installing two modules of the same specification, as noted above
  • Timings - Timings are the delays at which SODIMM memory modules operate and are likely to vary between laptop memory not only in terms of various brands but also different models of the same brand. If the two SODIMM memory modules you install feature different timings then the slowest set from the two will be selected during operation. This will void any performance benefit of the faster SODIMM memory module, instead forcing it to run at the timings of the slower installed SODIMM memory module
  • Speed - The supported speed of a SODIMM memory module, otherwise known as its frequency defines how fast or slow the memory operates. Similarly to the case of memory timings as noted above, should you install two SODIMM memory modules that vary in their supported frequency then the speed of the slowest module will prevail. Likewise to the case with memory timings, this will void any performance benefit of the faster SODIMM memory module, instead forcing it to run at the frequency of the slower installed SODIMM memory module

With the above in mind, it is now easier to understand Intel Flex Memory technology and therefore take a look at both symmetrical and asymmetrical dual channel mode.


Symmetrical dual channel mode is activated whenever two identical SODIMM memory modules are installed. These must be the same capacity and specification. Where applicable, such memory configuration yields the best performance as both SODIMM memory modules can be accessed in parallel providing more bandwidth to software.


Asymmetrical dual channel mode is activated whenever two different SODIMM memory modules are installed, either varying by their capacity or specification. Where applicable, such memory configuration yields reduced performance as both SODIMM memory modules can be accessed in parallel but only to a certain range. This range is determined by the capacity of both installed SODIMM memory modules and is best illustrated on a live example.


For example, in a laptop that has 1x 1GB and 1x 2GB DDR2 SODIMM memory modules installed, this range will be 2GB. The exact value stems from the common memory address space of the two SODIMM memory modules, which in this case is 2GB because each module has a memory address space of up to 1GB each, which when multiplied by the two modules results in 2GB. Consequently, 1GB from SODIMM memory module "A" and 1GB from SODIMM memory module "B" will run in symmetrical dual channel mode whereas the remaining 1GB found in SODIMM memory module "B" (assuming this module has a capacity of 2GB while "A" has 1GB) will run in assymmetrical dual channel mode. Performance in such cases will be somewhat diminished. Laptop manufacturers often take advantage by installing an odd number of memory to cut the BOL (Bill Of Materials) manufacturing cost at the expense of the buyer receiving a laptop that is not optimally configured.


Should optimum memory performance in your laptop be important to you then you should always attempt to either buy a laptop that is already configured to support the prerequisites of symmetrical dual channel mode, or seek to install identical SODIMM memory modules as an aftermarket upgrade procedure.


Learn more about laptop memory in part 2 of the Laptop Memory Upgrades Guide.


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