According to Microsoft’s support forums, a user complained that his Surface RT running the latest version of the company’s Windows 8.1 Consumer Preview was seeing an extreme power decrease while in standby mode. The user also noted that a driver known as “Microsoft UART V2” seemed to be causing the issue.
Microsoft’s support team contacted the user and requested he try switching his Bluetooth to on to save battery life. Right away, this seems to be an odd solution; turning on your Bluetooth radio should decrease your device’s battery life – not improve it. That being said, as soon as said user turned on his Bluetooth radio, his issue disappeared.
The folks at Microsoft explained why the issue fixed the problem:
Powercfg /sleepstudy reports any issues that are preventing the CPU from entering its lowest power state during Connected Standby (e.g. screen is off). In this case, the state of the specific UART controller is preventing the CPU entering its lowest power state. This UART happens to be connected to the Bluetooth radio on Surface. Unfortunately, the bug that causes this bad state occurs exactly when the Bluetooth radio is turned off in PC Settings.
As with all Consumer Previews and Betas, we expect to see a few bugs from time to time. It is very certain that Microsoft will fix the issue before Windows 8.1 is released to the mass public.
Have any of our readers been experiencing this issue themselves?