Overclocking nMP

Discussion in 'Mac Pro' started by islade, Apr 3, 2014.

  1. islade macrumors newbie

    Joined:
    Mar 6, 2014
    #1
    Hi,

    From what I have read, I can overclock my CPU/GPU while running bootcamp in windows, but there's nothing available to overclock CPU or GPU while running OS X.

    Is that correct, or did I overlook something?
     
  2. handsome pete macrumors 68000

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    Aug 15, 2008
    #3
    Those Xeons aren't really "overclockable" on either OS.
     
  3. Tutor, Apr 3, 2014
    Last edited: Apr 3, 2014

    Tutor macrumors 65816

    Tutor

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    #4
    Sandy and Ivy bridge Zeons are overclockable by at max 1.0755% in Windows running on a motherboard whose bios allows overclocking. The reason why the overclocking potential is much lower than with Nehalems and Westmeres, is that the newer CPUs link too many other things to the clock speed, such as PCIe; so if you overclock a Sandy or Ivy Bridge Xeon, then, unlike with the Nehalems and Westmere where you were also overclocking only the bus speed (which I like) and memory speed (also which I like, but it necessitates memory with higher speed potential), with the newer chips you're also overclocking your video cards' connection, your SATA, i.e., your SSD and hard drive connections, your USB connection speed, etc., many of which will cause a crash when the PCIe speed is increased substantially. Thus, to overclock OSX, you need a PC with a compliant motherboard bios and turn it into a hackintosh and the most you'd get from Sandy and Ivy Bridges is a modest increase in the speed because that 1.0755% is a cap, i.e., you're not even guaranteed to get that.
     
  4. islade thread starter macrumors newbie

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    Mar 6, 2014
    #5
    Sweet, thank you :)

    So... GPU overclocking... I guess I can run a "MSI Afterburner" style tool in windows. Is there any equivalent tool for a Mac?
     
  5. Tutor, Apr 3, 2014
    Last edited: Apr 3, 2014

    Tutor macrumors 65816

    Tutor

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    #6
    GPU overclocking will affect only your video card. I'm not aware of any software utility that currently allows it to be done on a Mac in OSX with the latest GPUs, but if there is such a tool my guess is that it is applicable only to AMD/ATI video cards, for as I recall there was once such tools because I recall using them. But that was a long time ago. Maybe someone else has more current info.
     
  6. beaker7 macrumors 6502a

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    Mar 16, 2009
    #7
    Considering that the thermal and power limits of nMP are already easily reached under load in stock configuration, I'm not sure what over clocking would do for you.
     
  7. Tutor, Apr 3, 2014
    Last edited: Apr 3, 2014

    Tutor macrumors 65816

    Tutor

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    #8
    Good Point. If I had a nMP and went about overclocking the GPU or installing a hotter running CPU, I'd definitely have to come up with some innovative solutions to increase the cooling, because if you cause it to overheat, the performance potential will drop via throttling. What's the diameter of the inner opening at the top of the case, measured at about a quarter of an inch from above the current fan and how deep is it from the very top of the case (measured from the inner surface at the top, i.e., where the tips of your fingers would be if your grabbed the system from that opening at the top) to a quarter of an inch from the current fan - try to be as exact as possible?

    If your wondering where I'm going, I'd say increasing the cooling potential by trying to find an additional (maybe), more powerful, but quiet, sucker - literally. I suspect that if this can be done that it would increase the performance of a nMP even if you did nothing else to it, for coolness is one of the primary factors for Turbo Boost to kick in and to increase the Turbo Boost to higher stages. So esthetically, I'd be looking for a pretty or macho or whatever else suits your fancy, black, quiet, circular fan. Who has the stats on the cooling potential (how much air does it move in a designated time unit), speed (RPM), speed stages, noise level (DB) and power draw of the stock fan?
     
  8. Riwam macrumors 6502a

    Riwam

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    #9
    Didn't Apple already make that research?

    .............................
    Don't you believe that before building their nMP the engineers of Apple already discussed all the possibilities of disposing of the generated heath and chose accordingly the size and exact shape of their only fan? :confused:
     
  9. Tutor macrumors 65816

    Tutor

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    #10
    I would have hoped so, but my doubt is fueled by some postings in this forum that the higher and highest Turbo Boost stages of the CPUs in the nMP are seldom, if every, reached.
     
  10. Zinn macrumors member

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    Nov 3, 2006
    #11
    Power usage goes up logarithmically with frequency. The nMP's PSU is 450 watts and under full load (at stock settings) you're already getting close to that.

    Even if heat weren't a factor (it is), there's no way you could overclock it without putting serious strain on its power delivery circuitry. At least it will make a good trash can when you burn it out :)

    If you want a PC you should buy a PC!
     
  11. Riwam macrumors 6502a

    Riwam

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    #12
    ......................
    Not being at all an expert, I am curious how can a third part (OWC) offer CPUs with higher working speed and still avoid killing the nMP because of the additional unavoidable heath added in this way?
    I assume that Apple knew perfectly well that the 8 and 12 core CPUs in their nMP could not work as fast as their 4 and 6 core CPUs precisely to avoid overheating.
    I do not believe that OWC found some magic way to solve this dilemma and if additional heath will reduce by itself the working speed of those CPUs they try to sell, the people who buy such a thing investing a lot of money and risking to void Apple's coverage, do not get any true advantage. :confused:
     
  12. Zinn macrumors member

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    Nov 3, 2006
    #13
    Intel's chips are specified to operate within a wattage range. The chips Apple is using in the nMP are Xeon chips with a TDP of 130 watts. That means that under full load they will rarely go above 130 watts of power usage.

    There are other Intel chips available at various price points that squeeze more speed out of the same wattage. Typically these chips are using better silicon, or offer less cores. Everything OWC is offering is within the same 130 watt operating watch as Apple's stock chips.

    There are also Xeon chips that run at 150 watts, such as an 8 core that runs at 3.4ghz ( http://www.newegg.com/Product/Product.aspx?Item=N82E16819116937 ). Those would definitely not be supported in the nMP.

    But my point is, these chips are designed to run at a carefully engineered power threshold. When you overclock you raise the power requirements significantly. A small bump in speed goes along with a huge bump in power, and it will exceed the ability of the machine's power delivery circuitry. The fact that they squeezed 2 high end GPUs and a 130 watt Xeon into a 450 watt TDP is already pretty amazing, but there is not a lot of breathing room there.
     

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