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DDR memory speeds and compatibility

October 15, 2025

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Adding more memory to your PC is one of the best and easiest ways to improve system performance. But before clicking that “buy” button on this or any website, it’s important to make sure the memory you are buying is compatible with your PC.

DDR5 memory is the latest generation of memory for computing applications and offers many benefits over previous generations of memory including lower latencies, higher speeds, and more. One thing to keep in mind is that memory needs to be the same type - memory modules are not forward or backward compatible in terms of generation types so DDR5 will not work in DDR4 or DDR3.

Memory is designed to be backward compatible within its generation, so generally speaking, you can safely add faster memory to a computer that was designed to run slower memory. However, your system will operate at the speed of the slowest memory module installed.

We recommend that you use either the Crucial Memory Advisor™ or Crucial System Scanner to find the right memory for your computer. Rather than give memory modules catchy names, the industry refers to modules by their specifications. But if you don't know a lot about memory, the numbers can be confusing. Here's a short summary of the most popular types of memory and what the numbers refer to.

Generations of memory explained

For double-data-rate memory, the higher the number, the faster the memory and higher bandwidth. Occasionally DDR memory is referred to by a "friendly name" like "DDR4-3200" or "DDR5-6400." When written this way, the number after "DDR" represents the generation. The number after the generation refers to the component's data transfer rate per second (/s). When referenced by the industry name, the numbers that follow "PC" and the generation refer to the total bandwidth of the module.

DDR5 speeds


Friendly nameIndustry namePeak Transfer RateData transfers/second (in millions)
DDR5-4800PC5-3840038400 MB/s4800
DDR5-5600PC5-4480044800 MB/s5600
DDR5-6000PC5-4800048000 MB/s6000
DDR5-6400PC5-5120051200 MB/s6400
DDR5-7500PC5-6000060000 MB/s7500
DDR5-8500PC5-6800068000 MB/s

8500


DDR5, the most recent released standard, features speeds starting at 4800 MT/s, with even faster speeds being made possible with new technologies such as LPCAMM2 form factors and clock drivers becoming a part of newer modules. Optimized for gamers, professional designers, and enthusiasts who need to maximize data rates, DDR5 is for those who want the most from their system. Crucial Pro DDR5 modules typically have faster speeds, lower latencies, and unique design and heat spreaders. 

DDR4 speeds


Friendly nameIndustry namePeak Transfer RateData transfers/second (in millions)
DDR4-2400PC4-1920019200 MB/s2400
DDR4-2666PC4-2130021300 MB/s2666
DDR4-2933PC4-2340023400 MB/s2933
DDR4-3200PC4-2560025600 MB/s3200
DDR4-3600PC4-2880028800 MB/s3600
DDR4-4000PC4-3200032000 MB/s4000
DDR4-4400PC4-3520035200 MB/s4400

DDR4 speeds start at 2400 MT/s, and for systems manufactured from 2014 to 2020, DDR4 enables even greater performance with lower power requirements compared to prior generations. 

DDR3 speeds


Friendly nameIndustry namePeak Transfer RateData transfers/second (in millions)
DDR3-1066PC3-85008533 MB/s1066
DDR3-1333PC3-1060010667 MB/s1333
DDR3-1600PC3-1280012800 MB/s1600

About adding faster memory ...

It may seem confusing, but faster memory will not necessarily make your system faster. You can't speed up your computer by adding faster memory if any of the other components in your computer (your processor or other memory modules) operate at a slower speed.

Keep in mind that the right memory for your computer is the kind of memory it was designed to take. Check your system manual or look up your system on the Crucial Upgrade Selector or use the System Scanner to find the perfect memory for your system.


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