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Micron
PC1600 or PC2100?
The first question you'll face is PC1600 or PC2100? The answer to this question depends on two important factors: your motherboard and your CPU. While a motherboard's chipset may support DDR memory, you will need to verify that it supports PC2100 DDR SDRAM, as some early models of DDR-enabled motherboards only supported PC1600. In addition, you will need to verify that the CPU for your computer can support PC2100. PC1600 DDR is designed for a motherboards and processors with a 200MHz front side bus (100MHz doubled), and PC2100 DDR is designed for a motherboards and processors with a 266MHz front side bus (133MHz doubled). In order to use PC2100 DDR SDRAM, make sure your CPU supports a 133MHz front-side bus (fsb). Several Intel Pentium III processors support this bus type. For AMD Athlon processors, look for the Athlon-C processor, which features a 266MHz front-side bus. You will get the fastest performance by combining a motherboard with 266MHz front side bus, a compatible CPU and PC2100 memory. Crucial's Memory Selector? will help you select the DDR memory best suited for your system.
You can install PC2100 in a system designed for PC1600. However, your computer will only run as fast as the slowest component installed. For this reason, if you have a 200MHz front side bus, you're probably better off purchasing PC1600 since PC2100 is more expensive and won't make your system any faster. The only exception to this rule is if you're planning to upgrade to a 266MHz front side bus later on. In this case, you could install PC2100 in your 200MHz system now and move the same memory to your 266MHz system later to avoid buying memory twice.