CPU and RAM speed question

naomelixes used Ask the Experts™
Hi there!

Quick question (or at least I hope so):

I have received a business proposal for the purchase of a few Dell PowerEdge R710 and R410 servers. In this proposal, some of the servers have Intel Xeon E5506 CPUs along with 1333MHz Dual Rank RDIMMs.

I have accessed Intel's data sheet for the E5506 CPU and have seen the memory specifications, which are as follows:

Max Memory Size (dependent on memory type)      144 GB
Memory Types       DDR3-800
# of Memory Channels       3
Max Memory Bandwidth       19.2 GB/s
Physical Address Extensions       40-bit
ECC Memory Supported       Yes

My question is: does this, in fact, mean that, with this CPU, I won't be able to take advantage of the whole RAM speed?
If so, is there any alternative, so I can in fact use my whole RAM speed (overclocking settings, etc.)?
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Top Expert 2014
Yes, it means that the 133MHz RAM will run at 800MHz, the only alternative I know of is using a CPU with faster memory channels, e.g. E5520


TYVM, I assumed that was the case, but still, I had to be sure.
It doesn't make sense to me, why someone would send me this proposal, then.
I will wait for a bit to see if someone else can give any other valuable input, if no one does, I will close and award you full points.

Could be down to costings, faster bus speed cpus would be more expensive, although I would expect slower memory to match the CPU in order to maximize cost savings.
Gary CaseRetired
Most Valuable Expert 2013
Top Expert 2009
There are two likely considerations ...

(a)  DDR3-1333 is actually less expensive in many cases than slower modules ... it's a simple case of supply vs. demand.    Since it will work fine at lower speeds, there's no particular reason to use slower modules.     Note also that you likely get better CAS latency running at lower speeds than you would with lower-rated modules.

(b)  Using the higher speed modules also "future proofs" your system should you later decide to swap the CPU for a faster one that can use the higher bandwidth memory modules.

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