The CPU throttling issue primarily affects the Surface Book 2 and the Surface Pro 6, as per complaints we have come across on Reddit. It is not clear what exactly is causing the issue that is clocking down the CPU to just 400MHz and affecting usability, but some users point the issue towards an Intel CPU flag called BD PROCHOT (bi-directional processor hot). Based on the user reports, the throttling appears to stop when the AC adapter or Surface Dock is disconnected, but some users also suspect it to be an issue generated by third-party antivirus software.
In case you are unaware, the BD PROCHOT is put into place to ensure that the CPU runs at a lower clock speed when an abnormal spike in temperature is detected. The flag is enabled not only when the processor is hot, but can also jump into action if another component in the vicinity of the CPU overheats. It is not clear whether rolling back to the older driver update fixes the issue.
“We are aware of some customers reporting a scenario with their Surface Books where CPU speeds are slowed. We are quickly working to address via a firmware update”, a Microsoft spokesperson was quoted as saying by TechRepublic. However, Microsoft is yet to explain what exactly is causing the throttling issue on the Surface Book 2 and the Surface Pro 6 in the first place.
Moreover, it appears that the new driver seeded by the recent firmware updates for Surface devices has also generated some Wi-Fi connectivity issues. As per user complaints on the official Microsoft support forum, the updated Wi-Fi driver arriving with the recent firmware updates severs connectivity with 5GHz networks.
The first-gen Surface Book, Surface Pro Gen 4, and the Surface Pro 6 are among the devices affected by the Wi-Fi issue. Users who reverted back to older drivers were reportedly able to restore normal 5GHz connectivity on their surface device.