Memory speeds

If you've been shopping for a memory upgrade you've probably seen the memory speed (or memory bus clock rate) referenced as one of the specifications. This was probably listed in megahertz (i.e. 133MHz, 266MHz, 333MHz) or as PC____ (i.e. PC133, PC2100, PC2700). Memory speed refers to the rate at which operations are executed, or the data rate. Below you'll find the memory speeds available for each kind of memory:

SDRAM:

PC66 or 66MHz
PC100 or 100 MHz
PC133 or 133MHz

DDR:

PC2100 or 266MHz
PC2700 or 333MHz
PC3200 or 400 MHz

DDR2:

DDR2 3200 or 400 MHz
DDR2 4200 or 533 MHz

Within each memory category, you can usually install any of the categorized speeds. However, the memory you upgrade with will clock down to the lowest memory speed that's already installed. In addition, some front side bus speeds will automatically "clock-down" memory speed. The best way to ensure what speed you need is to check what you already have or check your system specifications with your manufacturer or with our memory configurator.