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gpsd
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Xeon x5679

I have had a bit of free time on my hands lately and was looking at some processor upgrade options for a C20x (same motherboard as D20, or at least mine is). I came accross this cpu - xeon x5679. it is appealing because it can be had for quite cheap but seems to be placed between the x5670 and x5680 in terms of performance. But cpuid and compability info seems scarce. Anyone had any experience with this cpu?

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erik
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Re: Xeon x5679

[ Edited ]

under load the X5679 is identical to the X5675 except in being 130W 115W TDP rather than 95W and having a 1066MHz memory bus instead of 1033Mhz.

 

the X5675 has 2/2/2/2/3/3 turbo boost multipliers, putting it at 3.33GHz under full load and 3.46GHz under 1- or 2-core load.   the X5679 has 1/1/1/1/2/2 turbo multipliers, putting it at the same 3.33/3.46GHz frequencies.   all things equal, these two CPUs perform the same except for TDP.

 

if you can get the X5679 in a retail stepping at a good price then it's a decent processor.   i have an X5675 in my C20 and have been quite happy with it overall.

 

 

(edit: updated for clarification on specs)

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gpsd
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Re: Xeon x5679

They seem to be going for around $550 used (retail versions, not the confidential not for sale sample versions) - not sure if that is a great price, but is certainly a lot cheaper than x5680 or x5690.

 

By the way, where were you able to get that info - I couldn't find it anywhere. 

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erik
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Re: Xeon x5679

all of the four- and six-core westmere 130W TDP CPUs have either 1/1/2/2 or 1/1/1/1/2/2 turbo bins.   that's one of the drawbacks of the higher TDP is that they can't turbo as much—not like 133MHz really matters though.

 

$550 is cheap for a hex 6.4GT/s westmere regardless of speed.   you're essentially getting a 130W X5675 for half the price (or two for one in your case).

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gpsd
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Re: Xeon x5679

So how did you end up with those 130w tdp fansinks in your C20? And from a power consumption/heat perspective, the x5675 is optimal.

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erik
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Re: Xeon x5679

[ Edited ]

the heatsinks were procured through IBM parts when my C20 landed on my desk earlier this year.   at the time i had plans of getting 130W CPUs until a pair of X5675s fell in my lap.   the extra 5~10% from the X5680/X5690 didn't seem worth the added cost for my use (mostly CAD, solid modeling, and 2D graphic design).

 

(edit: typo)

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gpsd
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Re: Xeon x5679

I did a little more digging on this cpu and it would seem from some cpuid screenshots I found on cpu world and some user comments that the turbo mode is as Erik described, but the tdp is 115w and the maximum ram speed is 1066mhz instead of 1333mhz - so there will be a memory speed hit in using this cpu.

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erik
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Re: Xeon x5679

115W is possible but the last i heard it was 135W.   afaik CPU-Z pullsTDP numbers from their own database, not the chip itself.

 

not sure where you're seeing 1066MHz on memory though.   even this link on cpu-world.com shows it at 688.3MHz (which at DDR would be ~1333MHz).   there are no westmere 6.4GT/s QPI CPUs at less than 1333MHz that i've ever seen.   if it were 1066MHz memory then it would be at 5.86GT/s.   it isn't.

 

your best bet is to call intel and get it from the horse's mouth.

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psuturtle
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Re: Xeon x5679

The 5679 is an off-roadmap SKU.  I'll see if I can dig up the details.  Intel can sometimes get screwy with specs for these off-roadmap CPUs and the specs don't always align like one would think.

 

Just FYI, it's not one that we qualified specifically.  I don't think you would have any issues using it, but it's not officially supported.

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gpsd
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Re: Xeon x5679


erik wrote:

115W is possible but the last i heard it was 135W.   afaik CPU-Z pullsTDP numbers from their own database, not the chip itself.

 

not sure where you're seeing 1066MHz on memory though.   even this link on cpu-world.com shows it at 688.3MHz (which at DDR would be ~1333MHz).   there are no westmere 6.4GT/s QPI CPUs at less than 1333MHz that i've ever seen.   if it were 1066MHz memory then it would be at 5.86GT/s.   it isn't.

 

your best bet is to call intel and get it from the horse's mouth.



The 1066mhz I saw was user reported on another forum by someone who was surprised by the limitation (accuracy obviously cannot be confirmed). As well though, if you notice the cpu-z screenshot, it is on a system that allows overclocking of the cpu and likely the memory. But the ratio of fsb:dram is 2:8 - my understanding is that the 1333mhz capable x56xxx processors have a fsb:dram ratio of 2:10.