13" rMBP Processor Confusion

Discussion in 'MacBook Pro' started by MacLifer, Oct 29, 2012.

  1. MacLifer macrumors member

    Joined:
    Mar 18, 2011
    #1
    So the base 13" rMBP comes with a 2.5GHz dual-core Intel Core i5 processor.

    My late 2009 iMac has a 2.66 GHz Quad Core Intel "Core i5" I5-750.

    Admitting layman knowledge here ... does that mean my 3 year old iMac has a better processor than the 2012 13" rMBP? Or am I missing something regarding L2 cache or the chipset that makes the direct comparison not valid?

    Thanks.
     
  2. bill-p macrumors 65816

    Joined:
    Jul 23, 2011
    #2
    Overall your iMac has the better chip.

    Did you expect a different response?
     
  3. MacLifer thread starter macrumors member

    Joined:
    Mar 18, 2011
    #3
    Not really. But in making a purchasing decision, it is better to verify. I just find it kind of strange, that is all.

    So, the 15" rMBP has a better processor than my 2009 iMac, though, right?
     
  4. iScreamSanWitch macrumors member

    Joined:
    Jul 24, 2012
    #4
    You're comparing a desktop machine to a laptop.. which makes for an illogical comparison..
     
  5. KylePowers macrumors 68000

    KylePowers

    Joined:
    Mar 5, 2011
    #5
    Please don't be confused by the naming convention. Every architecture and die shrink (since its initial introduction) has had a Core i3, Core i5, and Core i7. It's mainly for the general consumer base - someone can obviously know nothing and guess that the i7 is better than the i5 and the i5 better than the i3.

    When comparing i5s for example, quad-core > dual core, and the higher the clock frequency (GHz), the better (things like low voltage, LV, and ultra-low voltage, ULV come into play too, but let's just ignore that for now). But that's only valid for processors released in the same year (aka same architecture or same die shrink). You can't just say a 2009 Camaro is better than a 2012 Camaro because it has a bigger engine or something (I'm not a car person, just trying to make an analogy), perhaps the 2012 is more fuel efficient and has newer technologies? It's precisely the same situation when comparing CPUs across different generations.

    Take for example this PassMark CPU benchmark for the 2.5GHz i5 in the 13in rMBP - it benches at 4000 (http://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i5-3210M+@+2.50GHz&id=815)

    Now compare it to this PassMark CPU benchmark for the 2.66Ghz i5 in your 2009 iMac - it benches at 3994 (http://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i5+750+@+2.67GHz&id=772)

    So in this case, they're close! But that's pretty amazing considering the processor in the rMBP is clocked at a lower frequency and is only dual-core! This will translate to equal performance, but less power consumption (especially considering the 22nm process and tri-gate transistor technology... and the fact that the iMac is a full-voltage processor (max TDP of 95W) where as the rMBP one is a low-voltage processor (max TDP of 35W)).

    Hope this helps!
     
  6. T5BRICK macrumors 604

    T5BRICK

    Joined:
    Aug 3, 2006
    Location:
    Oregon
    #6
    Keep in mind that you can't compare two processors by just looking at the clock speeds unless they're from the same "family."

    In this case you're comparing a first gen Intel i5 "Nehalem" family processor to a 2nd gen i5 "Ivy Bridge" family processor. It just doesn't work that way, as another poster has pointed out. The newer "slower" chip is actually just about as fast for some tasks.
     
  7. sectime macrumors 6502a

    Joined:
    Jul 29, 2007
    #7
    Maybe a correct one. It's an Ivy Bridge thing.
     
  8. derbothaus macrumors 601

    derbothaus

    Joined:
    Jul 17, 2010
    #8
    Kyle got it right. They are ... the SAME! Both execute 4 threads. The execution improvements in the Ivy chip makes up for the 100MHz clock disparity. I'd still rather have the real cores but a laptop needs battery life.
     
  9. MacLifer thread starter macrumors member

    Joined:
    Mar 18, 2011
    #9
    This was great. Thank you so much.
     
  10. CausticPuppy macrumors 65816

    Joined:
    May 1, 2012
    #10
    Each generation of chips has incremental improvements over the last.

    After 3 years of improvements, the net result is that the 2.5Ghz dual-core i5 is nearly as fast as the older 2.66GHz quad-core i5.

    The 2.5GHz i5 is also nearly double the speed of my 2.66GHz Core2Duo. And both chips have two cores. Turbo boost makes direct speed comparisons pretty useless though.
     

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