1.Why are you using sleep mode? It is a questionable feature for desktop PC. I had some problems in the past and i just refused from sleep mode completely.
Save your nerves instead of saving electricity
2.I want to see GPU-Z main screen
So I seemed to have solved the problem at least for now. What I did was reflash the latest bios on my mobo and the problem went away.
1. I don't know what to tell you other than I like the feature. But if i were unable to fix it that would have been my plan lol.
3. OS version 10.0.10586
Also to rule out the card I had a friend who has a different 480 put it in his system and it worked perfectly.
Old motherboard + new GPU it can explain such problem. Glad you sorted it out. If 17.1.1 driver works flawless for you,then you will probably will not have serious problems with your hardware in future.