According to Apple my 10-core iMac Pro should Turbo Boost to 4.5GHz when running single-thread tasks. The OS installed is Mojave.

When running a Mathematica code using only one kernel, Intel Power Gadget says that the frequency is 3.8-3.9GHz rather than 4.5GHz. The room temperature is 24ºC and the fans are going at the minimum speed. Note that a single-thread tasks is equivalent to a 5% load as their are 20 threads available thanks to Hyper-threading. See plot:

Perhaps the task I am running somehow does not demand the max Turbo Boost frequency. Could someone suggest a task/computation that could make my iMac Pro reach the advertised 4.5GHz?

Note that I am not asking what Turbo Boost is as this has been answered Here.

  • Re-encoding video ought to throw a bit at your CPU. Handbrake is a free encoding tool you could use. That won't guarantee you hit max turbo boost if the CPU starts getting thermally throttled though.
    – Scottmeup
    May 22, 2019 at 11:27
  • @Scottmeup how can i force Handbrake to run single thread?
    – Valerio
    May 22, 2019 at 11:28
  • Interesting question. Just tried it on my MacBook Pro and was also only able to reach 3.7GHz. CPU power and thermal management is quite complex these days. Cranking up the fans and having the computer idle for a minute helped a bit, but didn't quite get me there.
    – n1000
    May 22, 2019 at 11:58
  • To elaborate on my previous comment. I expect that you will not see max frequency under sustained load, but only as long as thermals allow. So I suggest you should wait for the Mac to cool down, power up the fans with third party software, launch the load.
    – n1000
    May 22, 2019 at 12:32
  • @n1000 what is the max Turbo Boost frequency of your MacBook Pro? Regarding thermals, starting from an idle state with low CPU temperature, one should at least get an initial burst at max Turbo Boost frequency, right? Managing the fans of the iMac Pro is tricky as Apple restricted it. For example, iStat Menus cannot do it.
    – Valerio
    May 22, 2019 at 12:53


You must log in to answer this question.

Browse other questions tagged .