Uploaded December 2011 | Updated September 2026, 2 weeks ago
At Crucial, we get a lot of questions about memory speed. Here are the main the differences between the speeds of the memory we sell on crucial.com
First and foremost, all of these memory types are double data rate -- or DDR -- memory.
Those numbers represent the speed of memory your computer was designed to support.
Crucial no longer carries PC2100 (DDR266) memory, but we do have PC2700 (DDR333) memory and PC3200 (DDR400). They are backward-compatible with PC2100.
And what does that mean?
Generally speaking, you can safely add faster memory to a computer that was designed to run slower memory.
Keep in mind your system will operate at the speed of the slowest module or system component.
There's another thing to consider-- memory has to be the same type to work. For example, SDRAM cannot be mixed with DDR, and DDR cannot be mixed with DDR2.
We recommend that you use the Crucial Memory Advisor™ or System Scanner tools to find the right memory for your computer.
Follow us on social media to get the latest Crucial news and product info:
Facebook - facebook.com/CrucialMemory
Twitter - twitter.com/crucialmemory
Instagram - instagram.com/crucial_memory
At Crucial, we get a lot of questions about memory speed. Here are the main the differences between the speeds of the memory we sell on crucial.com
First and foremost, all of these memory types are double data rate -- or DDR -- memory.
Those numbers represent the speed of memory your computer was designed to support.
Crucial no longer carries PC2100 (DDR266) memory, but we do have PC2700 (DDR333) memory and PC3200 (DDR400). They are backward-compatible with PC2100.
And what does that mean?
Generally speaking, you can safely add faster memory to a computer that was designed to run slower memory.
Keep in mind your system will operate at the speed of the slowest module or system component.
There's another thing to consider-- memory has to be the same type to work. For example, SDRAM cannot be mixed with DDR, and DDR cannot be mixed with DDR2.
We recommend that you use the Crucial Memory Advisor™ or System Scanner tools to find the right memory for your computer.
Follow us on social media to get the latest Crucial news and product info:
Facebook - facebook.com/CrucialMemory
Twitter - twitter.com/crucialmemory
Instagram - instagram.com/crucial_memory
