Re: [gentoo-user] new machine : CPU : 22 nm vs 32 nm

[Florian Philipp <lists@binarywings.net>]

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Am 25.07.2012 22:14, schrieb Volker Armin Hemmann:
> Am Mittwoch, 25. Juli 2012, 16:05:29 schrieb Philip Webb:
>> I've listed what's available at the local store,
>> which I trust to stock reliable items, tho' I wouldn't ask their advice.
>>
>> All the AMD's are  32 nm , while the Intel recommended by one commenter
>> -- Core i5-3570 4-Core Socket LGA1155, 3.4 Ghz, 6MB L3 Cache, 22 nm --
>> is  22 nm : it costs  CAD 230  & they have  3  in stock,
>> which suggests demand, but not the most popular ( 9  in stock).
>>
>> Isn't  22 nm  going to be faster than  32 nm  ?
> 
> no
> 

Lower transistor size gives you two advantages: Lower current (->
potentially lower power consumption and heat) and more transistors to do
something. The practical effects depend on what the chip maker does with
this.

>>
>> In the same price range, AMD offers  Bulldozer X8 FX-8150 (125W)
>>  8-Core Socket AM3+, 3.6 GHz, 8Mb Cache, 32 nm  ( CAD 220 ,  2  in stock).
>>
>> How do you compare cores vs nm ?
> 
> who cares?
> 

You cannot really compare this. If you can use more cores, e.g. because
you have an embarrassingly parallel application, by all means, get it.
Otherwise you should probably care more about single core performance.

>> How far is cache size important ( 6 vs 8 MB )?
> 
> depends on the architecture.
> 

In short, for all three questions: Look at benchmarks and look at the
TDP ratings if that is important to you.

nm numbers don't tell you anything that can be directly translated into
performance or other qualities. They only allow educated guesses. If you
really want to delve so deep into chip design, you could as well look at
pipeline depths, cache associativity and such alike (not that you should).

Regards,
Florian Philipp


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