Buffered & Registered Memory
Buffered modules contain a buffer to help the chipset cope with the large electrical load required for large amounts of memory. The buffer electrically isolates the memory from the controller to minimize the load that the chipset sees. However, unbuffered modules are the most common. In unbuffered memory, the chipset controller deals directly with the memory. There is nothing between the chipset and the memory as they communicate. Registered modules are unbuffered modules containing a register which delays all information transferred to the module by one clock cycle. This is usually done on modules with a large amount of memory to help ensure that the data is properly handled. The design of the computer's memory controller dictates which type of RAM must be used and buffered and unbuffered RAM cannot be mixed. Most buffered and registered modules also have ECC and are used in high-performance systems, where it is extremely important that the data is properly handled.