I'm having the same problem with a Z170-HD3P with Win 7_HP. From what I read, is something related to CPU auto voltage. Gigabyte is aware of the problem and is working on it. It has released a beta BIOS version that should fix it. As beta BIOS can lead to other problems, I'll wait for a stable an approved BIOS. Meanwhile my Power Options are set to High Performance to avoid entering Sleep or hibernation mode