Microsoft has confirmed it is testing a patch that will aim to fix a processor throttling issue for the Surface Pro 6 and Surface Book 2. We reported on this issue last month when numerous users of both devices complained of poor performance following a firmware update.

While being powerful devices, both the Surface Pro 6 and Surface Book 2 were left with performance matching older Intel Pentium processors. Indeed, speeds were clocked at a mere 400MHz and the problem stopped Intel’s Turbo Boost from working.

The problem is caused by an Intel CPU flag called BD PROCHOT. This is a flag that can be set by peripherals and instructs the processor to reduce its speed in an effort to manage system temperature.

While this Intel flag is a useful tool for machines where the CPU is pushing thermal limits. It is certainly not a new feature and not limited to Microsoft’s Surface devices. However, on the Surface Book 2 and Surface Pro 6 something keeps triggering BD PROCHOT even when it is not needed.


Microsoft confirmed the problem in August and we expected a fix to be rolled out this month. However, on Saturday the company confirmed a fix is currently being tested and will arrive in October.

“Thank you for reporting the issue. We are testing a fix that will release as soon as it passes our quality testing. When the fix is released it will be made available through Windows Update,” Eddy Atinda, a Microsoft employee stated.

Microsoft did not confirm that Intel’s BD PROCHOT was causing the problem, but it is still the most likely candidate.

Users report the throttling stops when the device is removed from the Surface Dock or other power outlet. Some users suggest it could be antivirus software causing the problem.