Earlier this month, Microsoft issued a flurry of firmware updates for its Surface lineup, including various models of the Surface Pro, Surface Book and Surface Laptop. Unfortunately, however, it seems the updates have started causing problems for some Surface Pro 6 and Surface Book 2 owners.
Reports on Reddit show Surface owners complaining about their PCs exhibiting excessive thermal throttling, with the machines operating at extremely sluggish clock speeds of 400MHz at times, even with the battery fully charged and plugged in.
While the folks over at TechRepublic posit this might have something to do with the BD PROCHOT flag for Intel CPUs, which allows device components to tell the CPU to throttle down if the peripherals' temperature is too high, Reddit users suggest disabling the flag may not fix the issue, either. Others report some success with installing the Microsoft driver pack for their devices. Yet others suggest a complete reset of the device may be the only way to ameliorate the throttling issue.
It's not entirely clear at this point as to what is causing this behaviour, but Microsoft has issued a statement saying it is "aware of some customers reporting a scenario with their Surface Books where CPU speeds are slowed" and that the company is "working to address [the problem] via firmware update."