My Radeon 7700 card had an issue from day one which was mostly manageable. Under Windows 7, 8, and 8.1, I would infrequently be unable to wake my monitor without unplugging the video cable and plugging it back in again. It didn't matter if I was using Displayport or DVI. This happened with a Samsung monitor and later with a new Dell monitor.
When I upgraded to Windows 10, the behavior changed.
I leave my machine running most of the time and allow the monitor to sleep.
Every morning when I get up, the monitor is no longer unresponsive, but the screen resolution has been reduced to the minimum setting. When I log in, trying to change the resolution is not possible because there are no other settings listed. Whether I log in or not, the fix (workaround) has been to unplug the Displayport cable and plug it back in. This works every time, but I still get what I call the icon crunch. All my work to arrange desktop icons is undone as the resolution change caused everything to be rearranged, even if I don't log in before resetting. My normal setting is 1920*1200, but what I find every morning is 800*600.
This does not seem to be related to number of hours away from machine because I'm at work longer that the amount of time I sleep. The display is fine when I get home from work, but not when I awake.
I have upgraded the drivers to the latest version with no change in behavior.
I turned off the monitor's power save features.
I am currently playing with the computer's power save features, trying to see if letting the computer sleep will help to reset properly.
Any other suggestions?