One stupid question about the CPU

Discussion in 'iMac' started by Jackotai, Nov 4, 2015.

  1. Jackotai macrumors newbie

    Nov 4, 2015
    the question is would that be the same performance between two CPU for example an i5 vs i7 (same standard) while the CPU are not fully loading or occupied? That say they are 50% occupied working on the same task, any different there?
  2. Samuelsan2001 macrumors 604

    Oct 24, 2013
    Well yes clock speed will make a difference, number of cores will obviously make a difference (although all imacs other than the base non retina 21 inch are quad core) and the desktop CPU's have no hyperthreading on the i5 so if your software leverages hyperthreading the i7 can be 40-50% faster in hyperthreaded applications.
  3. keysofanxiety macrumors G3


    Nov 23, 2011
    Lots of differences. You've got clockspeed, pipleline, efficiency, transistor count, CPU generation, number of cores, and the software itself - how efficient it is at utilising this. If an application was occupied at 50% on two different machines, but one machine is on a Core 2 Duo and the other is a quad-core i7, the quad-core will naturally be performing much better even if they're at the same percentage of use.

    I'm not sure if this answers your question (though admittedly I'm not 100% sure what your question is).

    The best reliable way to check a CPU's real-world power is to type the full model into This'll give you a number. The higher the number, the better the performance - simple as that. i3-3110M benchmarks at around about 3000. Core 2 Duo ranges from between 1200-1500.
  4. T'hain Esh Kelch macrumors 601

    T'hain Esh Kelch

    Aug 5, 2001
    The shortest answer to your question would be a no.
  5. Jackotai thread starter macrumors newbie

    Nov 4, 2015
    How about there are with the same psychical core, almost same Ghz but one with hyper thread on about 50% loading work task?
  6. AlifTheUnseen macrumors member


    May 17, 2014
    Psychical core…lol? Are we now in AI territory? Sorry, j/k

    If you have the same amount of physical cores, and you use only 50% of those, and both processors have plusminus the same GHz and not a lot of architecturial difference, then, yes, I think in this theoretical setup, the performance might be somewhat equal, afaict…

    I believe hyperthreading is only invoked in situations where all physical cores are saturated and there are threads waiting in the queue. I think hyperthreading is just useful under special situations. The difference in GHz is much more important (and an SSD, of course)
  7. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    Assuming both CPU have the same core count and speed.

    My understanding is the i7 will use all real cores first. So, if the loading is right at 50% on the i7, it's performance should be more or less the same as the i5 working at 100% (In fact, the i5 should be a bit faster in this case, but that's negligible in real world).
  8. Jackotai thread starter macrumors newbie

    Nov 4, 2015
    I have to apologise for my poor English:p and thank you all of your sincerely replies. Thanks again.
    One more thing, cozy I have bought and iMac 5K with a i5 CPU, and I bit regretting for not upgrading the CPU to the i7 instead of 395x. Cozy my original think is CPU performance are more or less the same in a certain clockspeed. Would you please advise what circumstances the i5 CPU will taking a disadvantage compare with the i7 CPU even noticable?
    I use my Mac for apperture(managing and editing), gaming, surfing, Photoshop..etc.
  9. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    Few games can use more than 4 cores, and only few filters in Photoshop are multi thread.

    Aperture won't receive update anymore, so no multi thread / GPU acceleration in the future.

    Surfing obviously can't saturate your i5.

    From memory, only Batman and GTA V can use more than 4 cores on my machine so far. By considering you have the top speed most up to date i5. I don't think CPU will be your limiting factor in the next few years (especially comparing to the GPU power in your machine, which is much much more limiting in modern game).

    So, it seems you won't miss anything by not choosing the i7. Unless most of the games are CPU intensive in the next few years and they are very well optimised for multi thread operation (the chance of this is almost zero). Or Adobe suddenly highly optimise Photoshop for multi core (this is possible, but it will only save you few seconds when applying a filter, no big deal).

    The i7 is much more useful in video work / multi VM scenario, but it seems you have nothing to do in this area.

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