[Beowulf] Opteron downrates DDR400 to DDR333 performance?

[V. B. Hunt]

NazarioJose at JohnDeere.com wrote:
> Hello, computer gurus -
> do any of you know if the AMD Opteron downrates the PC3200 400 MHz DIMMS 
> (DDR400) to 333 MHz (DDR333) performance  when the system has more that 2 
> Gbytes of memory installed?
>
> i was told that when an opteron socke has more that 2GBytes of memory, then 
> the cpu will automatically downrate the memory rate to an equivalence of 
> DDR333 memory.
>
> Thank you for your time.
> Jose.
>
>
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No, that is not true.  The test results at 
http://www.gamepc.com/labs/view_content.asp?id=opteronmemory&page=8 show 
that the Opteron interaction with memory is better in most cases when 
the memory is above 2 GB/processor die.  If your motherboard supports a 
dual-channel or quad-channel memory configuration, you can take more 
advantage of the Opteron's capabilities and high-bandwidth memory by 
installing more than 2GB of memory.  Just make sure all of the modules 
support the higher bandwidth or the on-die memory controller will 
automatically run at the frequency of your slowest module.

Brice Hunt