It can only be a guess without more information. Do you see any consistent error messages in the Event Viewer other than the Kernel power type message?
Have you set your system up to record the mini-dump files and if you have, could you attach the ones you have. There are some folks here that can read those and maybe give you some guidance.
Edit: I suppose I should mention 8.1 seems to have issues with some types of video drivers. For my GTX 680s, and immediate Nvidia driver update was offered. The WDDM driver that was also offered would cause a Blue Screen on my system, so I hid it and now it no longer seems to be offered.