I have a desktop running a fresh install of Windows 8.1 with a Radeon HD 6870 that's not working. I can't get into safe mode or force Windows to swap back to the onboard graphics chip, so I can't even use Windows -- it goes to a black screen once it boots.
Video crashed when my wife tried installing/playing Far Cry 3. It displayed some lines across the screen then went black. Stayed that way even after rebooting.
I tried everything, but all I could do to use the computer was boot into safe mode (this was on Windows 7, previously). I couldn't install/uninstall anything on safe mode, and system restore/rolling back video drivers didn't work.
Eventually I reformatted and installed Windows 8.1
It worked for a bit... then Windows Update tried to grab drivers for the video card. At first it failed to install the drivers. So I went into Windows Update, unticked all other updates, and watched it work on installing the drivers. Then, the same thing happened: it threw some lines across the screen then went black. The computer is still on, and working as far as I can tell, but the video is all black.
Now, I have a problem: I can no longer boot into safe mode! For some reason (as I read on a blog), F8/Shift+F8 aren't working because I have a UEFI BIOS and it's too fast booting to allow me to interrupt and boot into recovery mode. But every time I allow Windows to fully boot up normally, I just get a black screen after the Windows splash. I can't use the computer this way to tell it to switch back to onboard graphics or to use msconfig to tell it to boot into safe mode next time. I can't just unplug the video card and use the onboard graphics directly -- there's no DVI port on the back of the motherboard; it passes through the video card.
Help! Any ideas??