12-core only 2.7GHz, but 6-core 3.5GHz, which one is faster?

Discussion in 'Mac Pro' started by ApplesAOranges, Oct 26, 2013.

  1. ApplesAOranges macrumors 6502

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    #1
    So here´s the processor specs:

    4-core 3.7GHz
    6-core 3.5GHz
    8-core 3.0GHz
    12-core 2.7GHz


    Where´s the double processors? Why only single processor? Where´s the 2 x 12-core (24-core)? Why 12-core has so slow clock speed? Would getting a 6-core 3.5GHz be the fastest machine?

    Even with the previous Mac Pro people (people with lot of knowledge in these things) were saying that the clock speed is what matters, not the cores. And that the 6-core was the fastest machine.

    I´m confused. I don´t know what to buy. I really want the 12-core machine, but the 2.7GHz clock speed is really pathetic speed.
     
  2. ayeying macrumors 601

    ayeying

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    #2
    Clock Speed don't even matter too much anymore for performance. My desktop's Quad-Core 2.8GHz runs circles over my Dual-Core 3.0GHz, both i7 family when running Handbrake. I personally would get the higher cores vs faster speed, but that's just me.
     
  3. brock2621 macrumors 6502a

    brock2621

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    #3
    The clock speeds are most important with games, photoshop effects, SOME simple encoding apps etc.

    But if you are running rendering applications like cinema 4d, after effects etc. then the multicore with hyper threading is more beneficial than the high MHz.

    I just assume the more cores crammed into a single die would need to be clocked lower for heat dissipation.
     
  4. clamnectar macrumors regular

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    May 7, 2009
    #4
    The 4, 6, and 8 core machines all have turbo boost to 3.9 GHz, so there are basically no circumstances under which the 4 core is faster than the 6, or the 6 is faster than the 8. The 12 core would be slightly slower than the others for tasks that use 8 cores and fewer, but if something can use the remaining 4, it then gains a significant edge. That's an oversimplification, I'm sure, because of the different L3 caches and the nuances of turbo boost, but to boil it down, the 8 core core is likely the winner in terms of shining in the greatest number of situations.
     
  5. Umbongo macrumors 601

    Umbongo

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    #5
    The E5-1650V2 can boost up from 3.7GHz to 3.9GHz when one core is active and it will only maintain that clock speed while the temperature of the CPU is within the boundries set by Intel. It has 0/0/0/2 available bins of Turbo Boost, indicating it can go up 2 bins on 1 active core (100MHz each).

    E5-1650V2 is 1/1/2/2/2/4 so can also hit 3.9GHz on 1 core and could also maintain 3.7GHz across 4 cores, assuming it keeps within its thermal limitations that Turbo Boost requires to operate and it can even go up to 3.6GHz when using all 6 cores, but this is likely to be for limited periods. Intel only guarantee that it can maintain 3.5GHz because not all CPUs are created equally, even within the same models, and they can't know how good the cooling will be on them beyond their stock coolers.

    E5-1680V2 is 4/4/4/4/5/7/8/9, so interesting but not as fast as the 6 core has the potential to be under 6 cores.

    E5-2697V2 is 3/3/3/3/3/3/3/4/5/6/7/8.

    Don't buy based on turbo-potential, especially at this level with their 130W TDPs and the unknown capabilities of Apple's new cooling system.

    Real world performance wise you aren't going to notice a difference between the 4 and 6 core unless you can use more than 4 cores. If clock speed is paramount then the 8 and 12 core models, considering they will likely be in the region of $1,500 and $2500 upgrades, are not always going to be better.
     
  6. clamnectar macrumors regular

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    #6
    Thanks for the info. My post was based on comparing benchamarks, such as this one:
    http://browser.primatelabs.com/geekbench3/compare/86294?baseline=123580

    What you're saying is that, for example, if it were possible to do a "6 core-aware process test" the 6 core would outperform the 8 core by a noticeable amount, yes?
     
  7. Umbongo macrumors 601

    Umbongo

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    #7
    Most of those benchmarks are multi-core aware and don't tend to run for long periods (afaik) where you are more likely to lose turbo boost, so a 4-core isn't really going to shine in those benchmarks. There certainly are cases though. Maybe these days the situations where the 4-core would actually be of great benefit to someone are limited, but for some clock speed is all that matters and 4 cores is enough.

    Processor choice should be based on current experience with your hardware/software/workflow and looking at real-world benchmarks. It'll come down to whether $500 for 6 cores, $1,500 for 8 or $2,500 for 12 is worth it for those aspects of a workflow that hammer multiple CPU cores.

    Benchmarks don't tend to take in to account things like virtual machines either these days where extra cores can make a big difference in how someone works on a local system.
     
  8. Zwhaler macrumors 603

    Zwhaler

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    Jun 10, 2006
    #8
    If you're doing multithreaded processing then the more threads the faster it will process. Final Cut Pro rendering, video encoding, all will benefit from more cores over less faster ones depending on the ratio of corer count versus clock speed.
     
  9. Tutor macrumors 65816

    Tutor

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    #9
    That's the ticket. It's the needs of your software that should guide your choice as to which CPU is faster because the unstated object when sought is, "faster doing what?" Some predominately use software where core speed is most important and others - where core count is more important. We're not all running on the same racetrack.
     
  10. Tutor, Oct 29, 2013
    Last edited: Oct 29, 2013

    Tutor macrumors 65816

    Tutor

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    #10
    With fixed chip size, core crowding heats things up faster-> throttling.

    Clock speed matters and the number of cores matter, but what matters most is dictated by what software you're using. If you were one new to computer systems and hadn't decided on what software you'd be using, then, I'd suggest that you look at the speed question from the perspective of potential and this is how I'd recommend that you look at it:

    1) the 4 core system: 4 * 3.7 GHz = 14.8 GHz

    2) the 6 core system: 6 * 3.5 GHz = 21 GHz

    3) the 8 core system: 8 * 3 GHz = 24 GHz

    4) the 12 core system: 12 * 2.7 GHz = 32.4 GHz

    You can do the same analysis taking into account the various Turbo Boost stages and amounts.

    The reason why core speeds are made to decrease as core count increases is thermally related. By way of example, if you were in a hotel room on a cold winter night with no heating appliance, you might want that room packed with as many heat emitting, high metabolic human units as possible. But over heating a CPU causes it to throttle (down clock), at best, and to fail if it can't throttle down while the same pressures persist.

    On a related note, my theory why we haven't been shown by Apple the 12-core pricing is that Apple is still dealing with the throttling that was evident to me when Apple posted on Geekbench [ http://www.macrumors.com/2013/06/19/apples-new-mac-pro-begins-showing-up-in-benchmarks/ ] the performance of the E5-2697 V2 model. That Geekbench 2 score should have been much higher than 23,901. That's why I question whether Apple will be sticking with the E5-2697 V2 or should adopt the E5-2695 V2 because of its lower TDP. I've found that a GPU with lesser potential can outperform a higher potential one in Geekbench and other metrics because the GPU that doesn't find the need to throttle runs at full potential while the one with higher potential just overheats and slows down so much that you never see what it could do if it was tested in the proper environment. Being housed in a cylinder with just one fan for cooling everything w/the cylinder sitting on a desk just in front of the user who's running Logic loaded with plugins, an overheated CPU may soon yell, "I can't handle it - Its getting to hot. Fans, you better run at full tilt and let the goal of remaining quiet be damned." Apple takes great pride in the silent operation of its systems.
     
  11. VirtualRain macrumors 603

    VirtualRain

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    #11
    What's interesting to me, is they all have a TDP of 130W, but the 12-core can get double the work done of the 4-core within that power envelope. Clearly we're running into clock scaling problems… But let's face it, a Quad-core clocked at 8GHz would be far more interesting. :p
     
  12. Tutor, Oct 29, 2013
    Last edited: Oct 29, 2013

    Tutor macrumors 65816

    Tutor

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    #12
    I've added a note

    You may want to read a note that I added to my last post regarding heat. I'd rather have a single core clocked at 129.6 GHz (4x32.4 GHz) and that never needed to throttle because as it was ramping up to that speed, the ensuing heat was siphoned off and used to generate enough electricity that began a power loop to self-power the entire system. Bootup electricity would function only as a catalyst. "Intel, please give me a piece of that patent."
     
  13. BJonson macrumors 6502a

    BJonson

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    Aug 26, 2010
    #13
    Shoot, for the cost of the 12 core cpu you can buy another base mac pro and run it side by side with the other one for other tasks. 12 core macs just died folks. Rather have a new boat.
     
  14. phoenixsan macrumors 65816

    phoenixsan

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    Oct 19, 2012
    #14
    Some approach.....

    would say that multiple cores are relevant on situations where you run optimized apps that can use the cores with efficency. Others would say that raw computer power per se is all that counts.

    Boils down to the software used and the work done. Also multi-core setups tend to be higher priced.

    If I have to choose and have a budget constraint, I would go with the higher clocked CPU....:D

    :):apple:
     
  15. krell100 macrumors member

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    Jul 7, 2007
    Location:
    Melbourne, Australia
    #15
    Great thread!

    So if I use non multicore software i.e. Adobe suite, Cubase, NI then I'm actually better of with the quad?

    It seems that only hard core video editing and 3D rendering actually use those extra cores, right?
     
  16. BJonson macrumors 6502a

    BJonson

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    Aug 26, 2010
    #16
    I say 6 core is minimum. My 8 core 2008 mac pro runs circles around my 4 core 27" imac and the imac is i7 and the mac pro is core 2 duo. It feels faster, handles multiple tasks way better and just feels smoother.
     
  17. clamnectar macrumors regular

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    May 7, 2009
    #17
    One nice benefit of lots of cores is running a heavy task in one app (an app that uses 4 cores to 100%, say) and then being able to browse the web or do other tasks in other apps at the same time without everything getting choppy and unusable.
     
  18. flat five macrumors 603

    flat five

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    newyorkcity
    #18
    open activity monitor and watch the CPU usage throughout a typical day / typical tasks.. if all your cores are constantly or frequently maxing out then you'd probably be better of getting a 12 core.. if you're constantly seeing one core maxing out, you'll be better off with highest clock speed.

    super basic and there may be some holes in that but it's a good enough starting point if you're unsure about your CPU needs.
     
  19. Tutor macrumors 65816

    Tutor

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    #19
    Excellent point.
     

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