Registered memory

Registered memory (also called buffered memory) is computer memory that has a register between the DRAM modules and the system's memory controller. A registered memory module places less electrical load on a memory controller than an unregistered one. Registered memory allows a computer system to remain stable with more memory modules than it would have otherwise.

When conventional memory is compared with registered memory, conventional memory is usually referred to as unbuffered memory or unregistered memory. When registered memory is manufactured as a dual in-line memory module (DIMM), it is called an RDIMM. Similarly, an unregistered DIMM is called a UDIMM or simply "DIMM".

Registered memory is often more expensive because of the additional circuitry required and lower number of units sold, so it is usually found only in applications where the need for scalability and robustness outweighs the need for a low price – for example, registered memory is usually used in servers.

Although most registered memory modules also feature error-correcting code memory (ECC), it is also possible for registered memory modules to not be error-correcting or vice versa. Unregistered ECC memory is supported and used in workstation or entry-level server motherboards that do not support very large amounts of memory.^[1]