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Turbo boost and memory


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#1 anthdci

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Posted 19 June 2014 - 09:24

I have been asked for advice at work that I don't know the answer too. We are tendering for quite a few work stations. They spec they want is a Xeon E5-1620v2 and 16gb of DDR3-1866. But a company has come back considerably cheaper but with only DDR3-1600 memory. They want to know if this will make much difference. My experience was back when DDR2 was the king, and overclocking my AMD athlon64, where you needed to overclock the FSB inline with the memory speed, so you either needed faster memory, or better quality memory. I am obviously quite out of date.

 

My current thinking is, the 1620v2 is a 3.5ghz cpu stock. It has a 35x multiplier, so its bus is 100. That ties in nicely with the DDR3-1600 memory which according to wiki has a clock of 200 (I'm presuming being DDR it'll be doubled into the 100 bus of the cpu). Is this miles off how it actually works?

 

The next part is the turbo boost. It goes upto 3.9ghz. Does it do this by increasing the bus or the multiplier, or something else? If it is increasing the bus then will the DDR3-1600 memory struggle, and I'd be better getting the DDR3-1866

 

 




#2 Roger H.

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Posted 19 June 2014 - 09:59

If you are not planning on overclocking then DDR3-1600 will be more than fine. Hell if it becomes an issue, upgrading the RAM yourself might be cheaper anyways :p



#3 OP anthdci

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Posted 19 June 2014 - 10:09

If you are not planning on overclocking then DDR3-1600 will be more than fine. Hell if it becomes an issue, upgrading the RAM yourself might be cheaper anyways :p

 

I'm not overclocking it myself, it is the automatic turbo boost I was wondering about. When we are buying 150 of them I'd rather not upgrade the RAM myself  :pinch:



#4 Raa

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Posted 19 June 2014 - 11:00

When turbo-boost is in operation, you won't need to worry about the RAM speeds. (Y)

(Unless overclocking)



#5 +Phouchg

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Posted 19 June 2014 - 11:02

On these platforms there is only one clock - base clock or host clock, by default sitting at 100 MHz - from which all other clocks are derived using multipliers.

Turbo Boost on Patsburg works by changing core multipliers. Each core has its own and independent such ratio; nothing else changes when they are being changed.

Therefore, Turbo Boost does not impact memory. Memory has its own multiplier that is set and stays set unless base clock is changed.

 

There's a whole table of maximum memory frequencies each Xeon CPU is guarateed by Intel to be compatible. For E5-1620v2 it happens to be 1866 MT/s.

But it is true that 1866 will not bring any tangible increase over 1600 or even 1333... well, unless reduced CL is involved, but even then it's hardly measurable, and only matters when the system is being taxed at close to 100% both in terms of memory usage and CPU load.

 

That said, if your company had specced server parts for workstations, there must be serious reason for it, because that's probably the most damn serious gear one can get. I wonder what these reasons are.



#6 OP anthdci

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Posted 19 June 2014 - 11:12

 

That said, if your company had specced server parts for workstations, there must be serious reason for it, because that's probably the most damn serious gear one can get. I wonder what these reasons are.

 

I work for a university. The machines will be going into a student cluster for engineering students use do CAD design and they have to last 5 years before being replaced. Thanks for the advice, its very helpful.





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