That's it! After years and years with Radeons I'm switching to GeForce. When I upgraded from Windows 7 to 8 on my HD 5750 Desktop, I got these black bars. I could never get full CCC options to allow me to adjust the screen. No CCC driver pack would ever install, but hang somewhere during the install process. I had to run the Microsoft supplied video driver. Only the DigitalHDTVDefaultUnderscan registry fix got rid of the black bars, so I lived with it over the last 2 years.
Today I upgrade to Windows 8.1 and ta-da!, the black border is back. Text is crazy blurry. Of course the current 8.1 64-bit AMD driver pack still freezes during the install process. I was able to have the driver pack uninstall my limited function CCC and drivers, but it still won't reinstall. Still freezes during the install, so I have no CCC at all. And that DigitalHDTVDefaultUnderscan registry fix doesn't eliminate the border on this 8.1, like it did with 8.0.
There's no excuse for this. Goodbye!