Surface Pro 4's sleep never work well for me. I just get my old Surface Pro 4 replaced because of its defective touch screen. The new one still suffer from battery draining during sleep for Graphics and other causes.
Whenever I closed the type cover, the system never went cold.
So I run "powercfg sleepstudy" to find the problem.
- Intel HD Graphics was always awake during the sleep. For most sleep sessions, it would up for 30% time, for some sleep sessions, it never went to sleep.
- CPU was waked up too, but not as serous as Graphics
- The new problem since Windows 10 Threshold 2: Microsoft.Messaging waked system a lot of time, mainly for Skype. I didn't install Skype, this must be the integrated Skype Video and Messaging App.
I have said it before, and I hate to state it again: Surface Pro 4's sleep mode has no use at all.