Surface Pro 6, Surface Book 2 locked down to 400 MHz

Microsoft has become notorious for its botched updates that have introduced bugs as much as they fixed others. Quite a few times, those updates cause the worst kind of computer crashes or lockouts. No one seems to be exempt from this problem, including Microsoft's own Surface customers. Now it seems that another update has rendered its powerful Surface PCs almost useless by having their CPUs throttle down to just 400 MHz.

The problem, or at least the technical reason behind it, is nothing new. Users and technicians investigating the problem have traced it to a CPU flag called BD PROCHOT, short for bi-directional processor hot, that has been in existence for decades. There have also been reports years ago on that flag causing computers to throttle-lock as well.

In theory, that feature should only trigger when, as the name says, the processor runs too hot and needs to be throttled to avoid damage. In practice, a variety of peripherals can tell Intel CPUs to ease up on the processing to cool down temperatures. Unfortunately, Surface Pro 6 and Surface Book 2 owners are experiencing that for now immediately apparent reason at all.

Some users seem to have tied it with the Surface Dock or charging but that doesn't work. There is a third-party tool that prevents that throttle-lock from taking hold. Unfortunately, it also means that thermal throttling won't be working as normal. When the PC truly overheats, it will just shutdown.

Microsoft has told TechRepublic that it is aware of the issue and are working to get it fixed quickly. Not that users have much choice since their devices are completely unusable. Of course, this might not be the last time a Windows update will break PCs.