I am absolutely sure the system could support higher CPU frequency during this, but it does not go for it. Mathematica task is long but does not change in nature, it multiplies big matrices over and over again just with different numbers.Īll of this is followed with fans running on higher than default speeds, because I increase them with the Control tool. It's like the OS does not allow higher CPU frequency for the 'dangerous' thread, although the temperature can decrease eventually to <50C. Also the total core power increases, but only while this second process is running, as if the Mathematica process is forbidden to use CPU on higher clock. However, if I run another application on the side, the Intel Power Gadget can read higher core frequency (it shows just the average or the maximum, not per core/thread). After some more time (5-10 minutes) it will underclock for the second time, although the temperature is stable. The temperature reduces to ~60C, but until the end of computation this process never gets higher CPU nor Turbo Boost. The average temperature is probably 80C, but with Turbo Boost adjusting the clock, at some point temperature touches 100C and the CPU gets underclocked. At the start of computation the Turbo Boost is acting, the clock speed is higher and then after about a minute it abruptly reduces, simultaneously after the CPU temperature touches 100C. This might be Mathematica related, but so far I see no reason for underclocking so heavily.

While running some specific calculations in Mathematica it happens that the CPU gets underclocked from 2.9G to 2.3G in serial and even to 1.5G during parallel computations. I use Intel Power Gadget and Macs Fan Control tools for monitoring the CPU and fans speeds on MacBook Pro 2018 with i9.

Is this possible on new MacBooks and macOS ? I would like to have any direct control of CPU core clocks.

Macs fan control for high sierra 10.13