There is an issue with latest drivers (maybe all of them, but I only tried 17.4.1 and 17.4.2) and recent big Windows 10 update - since installing monitors don't turn off after specified time in control panel's power options. Instead they just show black picture, which still produces glow and doesn't save any energy.
I've tried DDU'ing drivers and without any GPU drivers they do go to sleep properly. But after installing 17.4.2 the issue comes back.
We've just published the 17.4.3 driver with full Creators Update support. Can you please try it and let me know if it help ?
I have the same problem since I changed to AMD, all drivers that I installed (16.12.1 + ) has this issue. I found that disabling "AMD External Events Utility" service fix this issue, but it have some downsides like Steam, Origin, Uplay etc taking longer to launch and Freesync needs this service Enabled to work.
Which card and monitor do you use? Connection type?(HDMI? DVI? VGA?)
Maybe it is a specific hardware/connection issue.
For now I have RX470 and GL2450 on DVI, the screen sleep feature works.
(Screen power LED's color changes from yellow to orange when it is sleeping.)
I do not try other type monitor though.
Creators Update with 17.4.3 installed.
I have R9 290, BenQ DisplayPort and ASUS HDMI monitors, happens on both.
It is probably more of a Windows issue than GPU drivers since it happens to all kinds of systems, including ones with Nvidia GPUs.
This issue doesn't exist if you let Windows install you graphics drivers automatically. It installs ancient 16.6 version of Crimson which doesn't have this problem.
Ironically I've had the reverse problem. A Windows 'restart' shuts down the monitor....which then refuses to respond for about 2 minutes or so before finally responding and the Windows swirly thing appears. It doesn't always do this....maybe about one restart in five. No amount of fiddling with the settings seems to fix it.