Registered memory: Difference between revisions

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Not to be confused with ECC memory, although modules are often both.

Registered (also called "buffered") memory modules have a register between the SDRAM modules and the system's memory controller. They place less electrical load on the memory controller and allow single systems to remain stable with more memory modules than they would have otherwise. Registered memory is more expensive because of the additional components, so it is usually found only in applications where the need for scalability and stability outweighs the need for a low price (servers, for example). Although most server-grade memory modules are both ECC and registered, there are registered non-ECC modules and non-registered ECC modules.

There is no performance penalty for using registered memory. Each read or write is buffered for one cycle between the memory bus and the DRAM, so the registered RAM can be thought of as running one clock cycle "behind" an equivalent unregistered DRAM.

References

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-::''Not to be confused with [[error-correcting code|ECC memory]], although modules are often both''
+::''Not to be confused with [[error-correcting code|ECC memory]], although modules are often both.''
-'''Registered''' (sometimes called "buffered") [[memory module|'''memory''' modules]] have additional components between the [[SDRAM]] modules and the system's [[memory controller]]. They place less electrical load on the memory controller and allow single systems to remain stable with more memory modules than they would have otherwise. Registered memory is slightly slower than unregistered/unbuffered memory, and more expensive as well, so it is usually found only in applications where the need for [[scalability]] and [[stability]] outweighs the need for speed and a low price ([[Server (computing)|server]]s, for example). Although many server-grade memory modules are both ECC and registered, there are registered non-ECC modules and non-registered ECC modules.
+'''Registered''' (also called "buffered") [[memory module|'''memory''' modules]] have a [[Hardware register|register]] between the [[SDRAM]] modules and the system's [[memory controller]]. They place less electrical load on the memory controller and allow single systems to remain stable with more memory modules than they would have otherwise. Registered memory is more expensive because of the additional components, so it is usually found only in applications where the need for [[scalability]] and [[stability]] outweighs the need for a low price ([[Server (computing)|server]]s, for example). Although most server-grade memory modules are both ECC and registered, there are registered non-ECC modules and non-registered ECC modules.
+There is no performance penalty for using registered memory.  Each read or write is buffered for one cycle between the memory bus and the DRAM, so the registered RAM can be thought of as running one clock cycle "behind" an equivalent unregistered DRAM.
 == References ==
 *[http://www.2cpu.com/articles/44_1.html 2CPU.com review]
-*[http://www.mushkin.com/doc/techSupport/papers/registered.asp Mushkin paper on registered memory]
+*[http://www.mushkin.com/doc/techSupport/papers/registered.asp Mushkin description of registered memory]