[KLUG Members] Reg ECC memory

[Bryan-TheBS-Smith]

Sanjay Chigurupati wrote:
> Hi, What's ECC memory? What are the
> advantages/disadvantages? Is it really useful

Error Correcting Code

Some newer memory controllers in chipsets have ECC, and ECC memory
allows single (and sometimes double) bit errors to be detected and
corrected.  During transmission and other processes, there is a
extremely slim chance that a memory bit will have its polarity
reversed by various electrical fields, etc...  When you add up all
the data access and writes done over the period of a year, the slim
chance becomes more of a possibility.  ECC not only detects these
errors, by using simple parity mechanisms, but can use additional,
but still simple, mechanisms to correct the error.

The advantage is, obviously, stability.  Hence why ECC is not only
recommended for servers, but some server chipsets, notably
multi-processor ones from ServerWorks (which high-end Intel boards
use) and even AMD's latest 760MP, actually require.  Many also
require "registered" ECC memory -- I will NOT go into "registered"
here (_long_story_).

The disadvantage of ECC is the additional overhead, which adds
latency to overall memory access.

Some chipsets do NOT support ECC at all.  As such, using ECC memory
in these chipsets does nothing.  Notably are many SiS chipsets, and
even a few Intel ones.

-- TheBS