So I bought myself a 7870, the first AMD card on this system.
Anyway I've tried several times with both drivers that came with the card and current Windows 8 drivers (12.4) and whenever I try it fails to install both the graphics drivers and the audio ones. Install manager, Transcoding and Control Center install fine.
I've tried using the whole uninstall-reboot-driversweeper-reboot-install sequence as this has made no difference.
I don't really know what else to try as the install error has no specifics about what is failing and/pr why. Just "Driver Install: the installation failed".