Difference between 19200 and 19200R ECC RAM

Hardware

This whole time I’d been assuming that both these SKUs of ECC DDR memory were equivalent. Rod Bland sorted me out at RamCity:

DDR4 modules can optionally [b]e “registered” (“buffered”), which improves signal integrity (and hence potentially clock rates and physical slot capacity) by electrically buffering the signals at a cost of an extra clock of increased latency. Those modules are identified by an additional R in their designation, e.g. PC4-19200R. Typically modules with this designation are actually ECC Registered, but the ‘E’ of ‘ECC’ is not always shown. Whereas non-registered (a.k.a. unbuffered RAM) may be identified by an additional U in the designation. e.g. PC4-19200U.

It never occurred to me that -R stood for registered/buffered. The Supermicro board in my new homelab machine only showed unbuffered memory compatibility, so I guess it’s just luck I didn’t accidentally pick up the wrong type.

ServeTheHome also has a great article.

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