RESEARCHUT -- Basic RAM Information:

What is the difference between PC2100 (DDR266), PC2700 (DDR333), and PC3200 (DDR400)?

PC2100 (DDR266) memory, PC2700 (DDR333) memory, and PC3200 (DDR400) memory are all types of Double Data Rate (DDR) SDRAM. The varying numbers refer to the different speeds of memory your computer was designed for.

Let's take a look at PC2100 (DDR266) to break it down simply.

PC2100 refers to the bandwidth of the memory. A PC2100 module has the bandwidth of 2.1GB/sec therefore it is referred to as PC2100.

DDR266 refers to the effective front-side bus speed of your system. While your DDR system or motherboard may operate a 133MHz front-side bus, its effective front-side bus speed is 266MHz because DDR effectively doubles the amount of data transferred per cycle that a non-DDR system would.

The same holds true for PC2700 (DDR333) which has a bandwidth of 2.7GB/sec and is designed for use in systems and motherboards which require a 166MHz front-side bus, with an effective front-side bus speed of 333MHz.

PC3200 DDR (DDR400) has a bandwidth of 3.2GB/sec and is designed for use in systems and motherboards which require a 200MHz front-side bus with an effective front-side bus speed of 400MHz.

Though DDR memory was designed to be backward compatible (meaning you can use PC3200 DDR in a computer designed to use PC2100 DDR or vice-versa), we always recommend that you use the Crucial Memory Selector to find exactly the right memory for your computer.


My computer uses PC2700 (DDR333). Can I use PC3200 (DDR400)?

DDR memory was designed to be backward compatible so generally speaking, you can safely add faster memory to your computer. For example, you can install a PC3200 DDR module in a computer that calls for PC2700 DDR. However, keep in mind that faster memory will not necessarily make your system faster. You can't speed up your computer by adding faster memory if other components in your computer (your processor or other memory modules) operate at a slower speed.