Microsoft’s Surface Book 2 and Surface Pro 6 devices are the latest laptop devices from the company that are supposed to deliver market-leading performance. However, owners of these two devices are being lumped with speeds more in line with old Pentium 2 speeds.

Users are complaining that Microsoft’s Surface products are throttling processor speed down to just 400 MHz. This is a power state that remains in place even when the Surface Book 2 or Surface Pro 6 are rebooted.

It seems the processor throttling is not a problem on Microsoft’s part. Instead, 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.


Problematically, it is not yet known which component is setting BD PROCHOT.

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.

“We are aware of some customers reporting a scenario with their Surface Books where CPU speeds are slowed,” a Microsoft spokesperson told TechRepublic. “We are quickly working to address via a firmware update.”