I've actually had a similar problem: having a HD 7700 and suddenly (I think after a windows update - the anniversary update(?) the problems started with having a black screen (actually, a black 'backlight' screen) when I rebooted the PC.
Now, to be sure: there might be different causes and reasons for such a failure, so I don't know if others will have exactly the same as me. For starters, with me it wasn't a problem with a dvi-d output on a TFT screen, but it WAS a problem when I tried to use the DVI-I (with adapter) to see something on my (CRT/VGA) screen. And it wasn't about a BSOD (as I've read someone here claim): it was just the screen going black, the PC and win10 started just fine. I'm sure of this, because I could enter through teamviewer (on another PC) and everything worked ok; I could even reboot from it.
That's also how I noticed it was never with simply restarting windows, but only after *shutdown' AND THEN starting it up again, I got the black screen.
Now, I tried numerous, numerous things. All what has been described here and elsewhere on the Net and more: installing the latest drivers, installing legacy drivers, reinstalling the entire windows, etc. Nothing worked. Very frustrating, I must say. I wasted so much time on this. But the hint I got was that it did work after restart, but not after shutdown, so I began to think it had nothing to do with the driver on itself (though it did work when I installed the generic windows drivers, but then one is limited to the resolutions and Mhz of those, which isn't much use neither). But since it used to work, but not after the windows update, surely it must be something to do with that and/or some setting or interference with the driver and/or a power-state or wake-up call of the PC. I tried to have the 'sleep' and 'power' settings doing different things, but that didn't seem to work neither. And then I found something that did.
For me, what solved it was this:
In windows 10, go to settings, system, power&sleep, additional power settings, choose what the power button does, change settings that are currently unavailable. After that, you'll see the grey-out checkboxes at the bottom becoming black so you can alter them, and then you un-check 'turn on fast startup'. It says it's 'recommended', but actually, that's what is causing the problem, and you really don't notice any delay when starting up, so I'm left wondering why it's put there. This could also be something that was put there during a large window-update, or it might have been 'checked on' at that time, or maybe they made some changes to it - but in any case, if you un-check that box and save it, and you had the same problem as me, chances are high it will solve your black-screen problem with the HD7700 as well.
Since it's a fairly easy thing to do, I'd suggest first trying out this before something drastically, like a complete re-install of win7/10 (as I did :-().
Greetz,
