Orion Poplawski wrote:
Jan Heichler wrote:

Don't forget DDR3-ECC memory which must be registered.


http://www.siliconmechanics.com/i22789/2U-4-node-server.php shows options for "ECC Unbuffered" or "ECC Registered". No idea what the practical difference would be. Anyone?

Registered DIMMs = higher density (i.e larger in storage size), but typically with a latency penalty since there is a register on the dimm for Address/Control signals that delay them by 1 clock cycle. So your CL4 Ubuffered DIMM would become a CL5 Registered. In addition Registered DIMMs have a PLL on the module to "freshen" up the clock signal.

Unbuffered DIMMs cant have so high density (i.e many chips) on them because of load to the control/address signals (more load = lower signal quality).

Cheers,
--Steffen
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