Third-party tool allows Mac Pro overclocking

Posted:
in Current Mac Hardware edited January 2014
In a rare example of the PC's performance tuning culture translating to the Mac, a new utility has surfaced that lets Mac Pro owners overclock their systems beyond Apple's official specifications.



The German edition of ZDNet has posted a utility dubbed ZDNet Clock Tool that allows owners of the Intel-based Mac workstations to push the clock speeds of their Xeon processors significantly higher -- with leaps from 2.8GHz to 3.24GHz for more recent systems.



Proven to work by those in the Mac community, the approach also increases the speed of the system bus and the memory as a result, though Apple's choice of hardware ironically suits it better to the process than many gaming-oriented parts for Windows computers: as the Mac Pro must use RAM with error correction, it prevents an excessive overclock from ruining data on the hard drive by making sure that only valid data leaves system memory.



The clock difference is enough to provide a tangible "free" upgrade in performance to the systems, though this isn't always measurable. In synthetic tests such as Geekbench, the software can incorrectly report similar performance even though timing the results proves that they're above what would happen at Apple's officially rated clock speeds.



However, unlike most overclocks, the technique requires a certain degree of trickery and carries an extra amount of risk. The current version of the tool works by loading a kernel extension into Mac OS X on boot that forces the clock speeds upwards immediately after the system starts. Without it, the Mac Pro would immediately revert back to its stock speeds the moment the system is rebooted, according to ZDNet. The initial beta app can also sometimes be overridden when the Mac comes out of sleep mode.



Like most overclocking, the technique is also limited by the nature of the hardware. At present, the German experimenters are unable to push past the 3.24GHz barrier without an inherently unreliable system. The faster processor speeds eventually overwhelm the memory and prevent it from correcting every error, triggering a kernel panic in Mac OS X that forces a reboot. High-performance third-party memory that operates above spec is described as the only real solution to this problem.



System time also falls out of sync without the expected clock rates and can't be corrected even by calibrating the computer online, the testers say. Instead, a reboot is necessary to at least temporarily provide accurate timekeeping.



While very much a beta version and potentially dangerous -- the possibility exists that the system won't start up correctly -- the utility is the first known that modifies core system performance on Intel-based Macs. Until recently, most overclocking utilities for Macs have dwelt on ramping up clock speeds on video cards to eke out more 3D performance for games.
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Comments

  • Reply 1 of 41
    futurepastnowfuturepastnow Posts: 1,772member
    Quote:
    Originally Posted by AppleInsider View Post


    Apple's choice of hardware ironically suits it better to the process than many gaming-oriented parts for Windows computers: as the Mac Pro must use RAM with error correction, it prevents an excessive overclock from ruining data on the hard drive by making sure that only valid data leaves system memory.



    Okay, seriously, I stopped reading right there.
  • Reply 2 of 41
    cbswecbswe Posts: 116member
    Thanks a lot! My 2,8GHz Mac Pro now runs 3,0 GHz =)
  • Reply 3 of 41
    Quote:
    Originally Posted by AppleInsider View Post


    The current version of the tool works by loading a kernel extension into Mac OS X on boot that forces the clock speeds upwards immediately after the system starts.



    Let me just add some comments:



    ZDNet Clock doesn't load a kext at boot time. It is dynamically loaded, when you start ZDNet Clock. After a reboot the kext will never be loaded, until you run ZDNet Clock again. This keeps things safe.



    If you reboot without turning the system off (shutdown), the Mac Pro keeps the speed you set with ZDNet Clock. In this case the system time runs at the correct speed and benchmarks report better results, because Mac OS adjusts the system time speed at boot time, but at no time afterwards. Also, the kext is not loaded, because it is needed only to change the bus clock. Once changed the kext can be unloaded.



    If you shutdown your computer and turn it on again later it will always run at stock speed. You need to run ZDNet Clock again.



    With pre-installed Apple RAM we were able to run a 2,8 GHz Mac Pro at 3,17 GHz 24 hours under full CPU and memory load without a single parity error, that had to be corrected.



    Using Kingston or Transcend RAM the same results could be achived at 3,24 GHz. Same specs as Apple RAM.



    Some noname RAM showed up errors at 2,83 GHz. A user reported RAM errors at 2,86 GHz using noname modules. One should probably check for parity errors in the system log when using noname RAM, even if the system runs at stock speed.



    -Christoph (Author of ZDNet Clock)
  • Reply 4 of 41
    winterspanwinterspan Posts: 605member
    I'm usually pretty knowledgeable with technical stuff, but I'm having difficulty understanding why the Mac Pro can't be pushed a lot higher? On the PC side, ever since the release of the original 65nm quad-core parts and especially now with 45nm, people have been pushing 2.4-2.6ghz parts up to 3.6-3.8ghz on air cooling! Is it the Xeon platform's requirement of FB-DIMMs the problem? Or something else that is Mac specific?
  • Reply 5 of 41
    Quote:
    Originally Posted by winterspan View Post


    I'm usually pretty knowledgeable with technical stuff, but I'm having difficulty understanding why the Mac Pro can't be pushed a lot higher? On the PC side, ever since the release of the original 65nm quad-core parts and especially now with 45nm, people have been pushing 2.4-2.6ghz parts up to 3.6-3.8ghz on air cooling! Is it the Xeon platform's requirement of FB-DIMMs the problem? Or something else that is Mac specific?



    The reason for this is, that ZDNet Clock doesn't increase the voltage of the CPU. Running a 2.4 GHz CPU at 3,8 GHz requires about 1.55 V, which may significantly shorten the CPU's life. An E5462 CPU (2.8 GHz) normally runs at 1.1125 V.



    In addition to that this would require a new SMC firmware, since Apple computers have an OS-independent fan control.



    -Christoph
  • Reply 6 of 41
    I wish they would make an Tiger version, it's Leopard only and my job keeps me at 10.4 Tiger right now.
  • Reply 7 of 41
    As if the MacPro needs to be any faster...
  • Reply 8 of 41
    8corewhore8corewhore Posts: 833member
    why?
  • Reply 9 of 41
    bloggerblogbloggerblog Posts: 1,819member
    Quote:
    Originally Posted by 8CoreWhore View Post


    why?



    You can buy a 2.8 and run it at 3.x ghz

    Big money savings.
  • Reply 10 of 41
    So this doesn't really mean much for someone that already has 3.2GHz?
  • Reply 11 of 41
    schutschut Posts: 8member
    Quote:
    Originally Posted by Xian Zhu Xuande View Post


    So this doesn't really mean much for someone that already has 3.2GHz?



    It means you wasted $1600.
  • Reply 12 of 41
    jeffdmjeffdm Posts: 12,946member
    Quote:
    Originally Posted by bloggerblog View Post


    You can buy a 2.8 and run it at 3.x ghz

    Big money savings.



    The percentage of speed increase isn't that much anyway. I don't see it worth spending more for a slightly faster chip, and I don't see it worth risking system stability, warranty or longevity for moderate boosts in speed using a hack. If it worked for Tiger, I would just underclock anyway, at least for the summer months, to generate a little less heat.
  • Reply 13 of 41
    jeffdmjeffdm Posts: 12,946member
    Quote:
    Originally Posted by wealthychef View Post


    I wish they would make an Tiger version, it's Leopard only and my job keeps me at 10.4 Tiger right now.



    I would not do this with a computer which you do paying work.
  • Reply 14 of 41
    jeffdmjeffdm Posts: 12,946member
    Quote:
    Originally Posted by Schut View Post


    It means you wasted $1600.



    I wouldn't say so. There are some quirks you get when using this program. A 2.8 overclocked to 3.2 doesn't necessarily behave the way a stock 3.2GHz does.
  • Reply 15 of 41
    MacProMacPro Posts: 18,141member
    Well it sounds as though Christoph thought this through pretty carefully to be as safe as possible. I have a new, recent edition 8 Core 2.8 Mac Pro and would love to try it. Is there a price on this product yet? Also is there a link to any tests done of real world applications such as FCPro rendering? I have both stock graphics card and an 8800 both on 30" ACDs, are there any timing issues using two graphics cards?



    JeffDM's usual learned and positive opinions aside, I can see this being very useful and cost saving in a working environment if the increased speed work on such things as rendering times. I am excited about the possibilities!
  • Reply 16 of 41
    cbswecbswe Posts: 116member
    An interesting effect is that when I use it my videos played in VLC becomes rather choppy with the sound and video, however QT does not. When I clock the CPU back to the original setting, VLC behaves normal again
  • Reply 17 of 41
    Quote:
    Originally Posted by Cbswe View Post


    An interesting effect is that when I use it my videos played in VLC becomes rather choppy with the sound and video, however QT does not. When I clock the CPU back to the original setting, VLC behaves normal again



    Similar peculiarities are exhibited when using EyeTV and ZDNet Clock. There's also a potential problem with TV programme scheduling courtesy of known time synchronising issues.



    Still, my 2800 hits 3100 with no memory errors (running +12Hrs continuously)
  • Reply 18 of 41
    asciiascii Posts: 5,941member
    Quote:
    Originally Posted by Xian Zhu Xuande View Post


    So this doesn't really mean much for someone that already has 3.2GHz?



    They can probably clock it to 3.4 or 3.6.
  • Reply 19 of 41
    MacProMacPro Posts: 18,141member
    Quote:
    Originally Posted by Cbswe View Post


    An interesting effect is that when I use it my videos played in VLC becomes rather choppy with the sound and video, however QT does not. When I clock the CPU back to the original setting, VLC behaves normal again



    That's encouraging for QT. Have you tried any tests on rendering speeds in QT and have you tried pro apps such as Motion and FCPro? Thnx.



    I will test myself ... I just found the link
  • Reply 20 of 41
    Quote:
    Originally Posted by Schut View Post


    It means you wasted $1600.



    Haha... maybe that would be true for you. We each have different uses for our computers.

    And I need my computer to work consistently and reliably.



    Quote:
    Originally Posted by ascii View Post


    They can probably clock it to 3.4 or 3.6.



    Reason why I asked is that what I've read makes it seem as if ~3.2 GHz is about as high as you can go (given memory limitations and such). Having faster processors in my Mac Pro isn't going to speed up my memory's capabilities. I probably wouldn't be using this sort of program anyway, but it will be interesting to follow.
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