After shutting Windows down normally or going to hibernate, the next time I try to start up the system, both of my two displays remain in their no-signal standby mode (normally the display indicator light turns green soon after powering up the system). To recover, I have to press the reset button and the power button several times, or disconnect the PC from the mains. If it recovers, the system boots up or resumes from hibernation normally. I never had such problems with my previous display adapter HD 7800. My suspicion is that the display driver leaves the adapter in a messed up state on D0 exit and only a complete power down or a deep reset fixes the issue.
I suspect the issue with normal shutdown also has to do with hibernate mode, since the Windows fast startup feature puts the system in hibernate mode instead of normal power off.
Windows 10 (previously Windows 8.1, which had the same issue)
MSI R9 390 GAMING 8G
Asrock A770DE+ Motherboard
AMD Phenom 9950 CPU
Overall the R9 390 has been a disappointment. I initially stumbled on the Windows Update downloading a bad driver issue and ended up reinstalling Windows, until I figured out what the real problem was. The first card broke down after few days of use and had to be replaced. Also Xbox streaming on Windows 10 crashes the PC, which I suspect is due to the display adapter.