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Thursday, February 10, 2011

How do I upgrade the Memory on my Dell Poweredge R710 Server?

By Kay Winchell, Technical Support, Velocity Tech Solutions.
How do I upgrade the memory on my Dell Poweredge R710 Server? It seems to be the most frequently asked question lately for our sales and technical support staff. With the Nehalem processors controlling the memory of that unit, things can be a bit tricky compared to the previous generation of Dell servers. There is a whole new set of rules for adding memory, so let’s get started.
The biggest lesson to be learned, in my opinion, is not to skimp on the memory when purchasing the R710 server! Sometimes it haunts you in the long run when trying to upgrade later on, and this is one of the Dell servers where that is definitely true.
Let’s summarize some of the rules for this new architecture.
1. Memory for the R710 server is made in Un-registered dimms (UDimms) and Registered dimms (RDimms).
2. Memory is allowed to run at 800Mhz, 1066Mhz and 1333Mhz speeds.
3. There are up to 3 memory channels that are connected to each processor socket and up to 3 dimms per memory channel. A processor must be in the socket to use the channels.
4. UDimms come in 1 or 2GB stick sizes and are limited to 2 Dimms per memory channel.
5. RDimms come in capacities up to 8GB sticks. RDimms and UDimms cannot be mixed.
6. If the processor has a QPI Speed of 6.4GT/s the following applies:
a. 1 Dimm in each channel will run at 1333mhz (35GB/Sec.)
b. 2 Dimms in any channel drops the speed to 1066Mhz (32GB/Sec.), an 8.5% reduction in speed.
c. 3 Dimms in any channel drops the speed to 800Mhz (25GB/Sec.), a 28.5% reduction in speed.
7. Memory can be balanced (3 dimms across each channel), or unbalanced (less than 3 dimms across each channel). When your memory is unbalanced you will lose about 23% of bandwidth.

Here are some simple suggestions for getting the most out of your Poweredge R710.
o Start with a processor that supports 1333Mhz Memory.
o Use Rdimms.
o Keep the dimm sizes the same.
o Think in 3s.
Select the dimm size that gets you closest to the capacity you want, although you may not get the exact capacity you want.
I hope that answers some of your questions.