[Beowulf] bizarre scaling behavior on a Nehalem

Tom Elken tom.elken at qlogic.com
Fri Aug 14 13:57:53 PDT 2009

> On Behalf Of Bill Broadley

> I put DDR3-1333 in the machine, but the bios seems to want to run them
> at
> 1066, 

How many dimms per memory channel do you have?

My understanding (which may be a few months old) is that if you have more than one dimm per memory channel, DDR3-1333 dimms will run at 1066 speed;
i.e. on your 1-CPU system, if you have 6 dimms, you have 2 per memory channel.

> I'm not sure exactly what speed they are running at.

Your results look excellent, so I wouldn't be surprised if they are running at 1333.


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