Okay, I just tried to make a post. Didn't realise I couldn't post links. Removed all the text I had written. Very annoying, but I'll try to write it again. Sorry if I sound brief I'm just tired of typing.

I just re-installed dishonored from Steam after a full reinstall of windows. All my hardware is the same (graphics card is ATI HD 6xxx series).

Game has a very bad graphical glitch where the screen is sliced into horizontal bars which are all moved around and sort of blurred at the edges, like shattered glass.

I can't take a screenshot because it just shows up black. I have, however, taken a photo with my phone of the screen. If you would like to see it, go to imgur dot com forward slash F2FzJoV. It is difficult to describe how it looks without a picture.

I have tried updating and rolling back drivers, I have tried reinstalling the game, I have tried verifying game cache integrity. None of that worked.

It's really messed up and I can't play the game, but I'd very much like to try it again. Can anyone help?

After reinstalled windows, did you install the Motherboard drivers from the Mobo makers website? Windows can apply some drivers that will get the mobo sort of working, but it's not fully ready to game.