Resolved Can someone help me understand processors

Discussion in 'Mac Pro' started by UncleSchnitty, May 25, 2014.

  1. UncleSchnitty, May 25, 2014
    Last edited: May 25, 2014

    UncleSchnitty macrumors 6502a

    UncleSchnitty

    Joined:
    Oct 26, 2007
    #1
    I am trying to figure out the trend with processors these days. Are Mac processors under-clocked? The thing I am trying to figure out is Mac Used to use the highest clock-speed they could and thats how they would advertise now it seems like they have tuned that back a little.

    I assume they use the same idea as car sales. Put a smaller engine(processor) put a turbo on it(turbo boost) then you get better gas milage(power consumption) but power when you need it(turbo boost numbers)

    Is that a fair analogy or am I missing something? Is that the whole reason for the nMP as opposed to the power guzzling MP tower?
     
  2. Umbongo, May 25, 2014
    Last edited: May 25, 2014

    Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #2
    No.

    Sort of. They are using the fastest 4-core and 12-core CPUs available to them.

    The 8-core is the fastest for single CPU systems and the only one designed for single CPU systems, but they could have used one for dual-cpu systems like they did with the 12-core, although Intel's list price is $334 more for 10% clockspeed (3.3GHz compared to Apple's 3GHz). There is a 3.4GHz 8-core for a bit more too, but it requires more cooling.

    The faster 6-core is almost twice the price for 100MHz more clockspeed and some L3 cache and not worth offering with how Apple go for limited options.

    They aren't offering dual-CPU systems now because sales were really small. Apple have used what Intel have available is all. Turbo boost is more "your CPU will do the advertised speed, but sometimes it might go higher".
     
  3. UncleSchnitty thread starter macrumors 6502a

    UncleSchnitty

    Joined:
    Oct 26, 2007
    #3
    So the regular listings that say 3.5 turbo boost to 3.9 is regular speed up to overclocked? that what I don't get. Like when I bought my tower it was just 2x3.2ghz quad-core. now with all this "turbo boost" I really don't understand it. Thats why I assumed it was underclocked to overclocked to save power.

    Sorry if these are dumb questions. Im pretty good at understanding things but Im just not understanding. thats why Im asking.
     
  4. reco2011 macrumors 6502a

    Joined:
    May 25, 2014
    #4
    Turbo boost is a way to balance single core performance on multi-core processors. Processors have a limited thermal / power envelop for which they can operate. With a single core design the core was clocked as high as possible while still falling within the thermal / power design. With multi-core designs the thermal / power envelop had to be shared among the various cores. This means the cores would have to be clocked lower in order to stay within the thermal / power constraints. This meant singled threaded tasks would run slower on a multi-core processor as the clock speed was lower. Thus one had to make a tradeoff.

    Turbo boost attempts to eliminate that trade off. The rated speed of a processor with multiple cores represents the speed the processor will operate at with all of its cores in operation. If you have a 150W quad core processor with a 3.5GHz base clock then all four cores, if in use, will operate at 3.5GHz. However if you're running a single thread application then turbo boost will "shutdown" a few of those cores and increase the clock speed to the remaining cores. Let's say that same processor has a single core turbo boost speed of 3.9GHz. Therefore the processor will increase the clock speed because the thermal envelop / power requirements will remain within the 150W specification. Therefore you no longer have to choose between higher core counts and higher clock speed. You get the best of both worlds.

    What I described is a very high level of what turbo boost does. If you'd like to know the details there are some very good explanation on the web. I like the following from Anandtech:

    http://www.anandtech.com/show/4528/the-2011-macbook-air-11-13inch-review/3
     
  5. UncleSchnitty thread starter macrumors 6502a

    UncleSchnitty

    Joined:
    Oct 26, 2007
    #5
    Very cool, thank you I think I understand how it works now. Very helpful.
     
  6. Yahooligan macrumors 6502a

    Yahooligan

    Joined:
    Aug 7, 2011
    Location:
    Illinois
    #6
    Also keep in mind that processor speed (GHz) has been uncoupled from performance for some time now. The newer CPUs may have slower clock speeds than their predecessors but they are faster. You can't compare CPU clock speeds from different generations to gauge performance between them.
     
  7. UncleSchnitty thread starter macrumors 6502a

    UncleSchnitty

    Joined:
    Oct 26, 2007
    #7
    Yes I do realize that. But at the same time I can say that my 2008 MP is faster than my 2011 MBA despite a few generation gaps hah. I was more so wondering why the turbo boot numbers and regular numbers. It was more of a for my information question. Sometimes I like to use this forum to learn (I know thats unusual these days, it seems more and more its used to argue and bicker hah)
     
  8. rambo47 macrumors 6502a

    rambo47

    Joined:
    Oct 3, 2010
    Location:
    Denville, NJ
    #8
    I guess you don't remember the old PowerPC days, huh? You young whippersnappers have it too good! << /old man rant >>
     
  9. UncleSchnitty thread starter macrumors 6502a

    UncleSchnitty

    Joined:
    Oct 26, 2007
    #9
    hah actually the first macs I really worked with were the G4s(we had a mac in the house around 95ish but I don't remember the model it had the rectangle system and a crt on top) I always wanted the cube hah. My first one that I bought and actually worked on was a G5 tower(I still have that and am always looking for uses for it in a modern world). So I do have my fair share of PPC experience.


    Edit: I was a little off it was earlier than 95 it was the Macintosh IIfx, all I remember is we used Claris works on it hah
     

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