Slow BootCamp due to Faulty Temperature determining Clock Speeds of Intel M5 Processors.

This issue is occurring on a Gold MacBook Retina 12" (Early 2016), with a Windows 10 BootCamp Partition. I used CPUID HW Monitor in order to read temperature readings, and the Intel Power Gadget 3.0 to chart out processor speeds for troubleshooting.

BRIEF:

On a Windows 10 Bootcamp partition, the average processor speed is 0.8Ghz. On OSX El Captain, the average speed is closer to 2Ghz, due to properly-working SpeedStep and Turbo Boost implementation.

I believe the decreased performance on the Windows 10 partition results because Intel is reading the SSD Assembly Temperature Sensor, instead of the CPU Temperature Sensor, as it does on OSX.

The temperature threshold for the SSD on Windows 10 in this implementation, is 44 degrees Celsius - a temperature which is almost always exceeded by even the lightest browsing.

DETAILS:

Intel Skylake processors come with SpeedStep and Turbo Boost, which control the clock speed of the processor, with the constraints of processor demand and thermal load. If a high processor speed is demanded for a sustained period, the temperature may exceed the envelope, and will subsequently be decreased in order to reduce the amount of heat being produced, putting it back within the safe range of operating temperatures. After temperatures have decreased, Turbo Boost will become accessible again.

On the Mac OSX El Captain side, this works properly. Clock speed for the Intel M5-6y54 ranges between 1.2Ghz - 2.7Ghz, as advertised. Speed 'underclocking' is determined by the temperature output of the CPU cores.

On the Windows 10 BootCamp partition, it's an entirely different story. Initially, it appears as if the processor is functioning properly, with the clock speed ranging between ~1.2Ghz-2.7Ghz based on demand. HOWEVER, when the 'SSD Assembly Temperature Sensor' exceeds 44 Celsius (~111 Fahrenheit), clockspeed is immediately reduced to 0.8Ghz. IT SHOULD BE NOTED, underclocking also occurs as a result of CPU temperatures exceeding 90 Celsius, but that is not the issue, because the SSD Temperature often operates on both the OSX and Windows 10 partition at temperatures exceeding 44 Celsius, while the CPU rarely reaches 90.

Here's where it gets messy:

- After reaching 0.8Ghz, it does not return to Turbo Boost speeds until the SSD Assembly Temperature Sensor reads less than 45 Celsius.

- The TC0P and TM0P Sensors may also be implicated in the SpeedStep calculation, but this is much more unclear.

- There is no correlation between processor temperatures and when Turbo Boost becomes available again on the Windows 10 BootCamp side. CPU temperatures range from 48-97 Celsius on Windows 10, PRIOR to underclocking. On OSX, on a sustained load with normal Turbo Boost operation, they hover between 65-92 degrees Celsius. They continue to hover in the upper-range of operational temperatures, NEVER needing to underclock below 1.2Ghz.

- Once Turbo Boost speeds have been reached once more, EVEN IF the SSD Assembly is less than 44 Celsius, attempting to utilize more processor speed (by loading a webpage for example), results in IMMEDIATE underclocking to 0.8Ghz. This could be seen as the exact opposite of Turbo Boost - a Turbo Slowdown. After a while, it gets 'unstuck' and goes back to functioning normally, until the SSD Assembly temperature is exceeded.

SOLUTION:

PRAM and SMC resets do not work. Fresh installations of Windows 10 by any method, do not work. Fresh installations of OSX do not work. This leads me to believe that it is simply a NEW driver related issue, relating to how the hardware and sensors interface through the software.

The only solution, at the moment, is to overclock your CPU to a midpoint between the Turbo Boost speed and the ADVERTISED (the true minimum on the hardware is 600Mhz) base clock speed of 1.2Ghz. I chose 1.8Ghz because at this point, even under full sustained loads, the computer dissipates heat effectively to keep it within the TRUE hardware, thermal operational threshold.

In order to implement this solution, I used ThrottleStop 8.10. The only boxes that I checked were "Set Multiplier (18T)," "BD PROCHOT," "Task Bar," and "SpeedStep." My processor temperature hovers around 50-80 Celsius, consistently. My SSD Assembly temperature now sits closer to 48 Celsius, with the computer on my lap, running a moderate load, and in a room at about 76 degrees Fahrenheit. I need to do more testing, but this seems pretty satisfactory.

Message was edited by: Zkhcohen