I just bought a new Asus HD7770. Having installed it, I powered it up, and it seemed to work fine.
However, after running a windows experience index text (out of curiosity) after one of the screen flashes, the screen was full of small purple dots!
This problem also included purple lines, and graphical problems in-game (see here: http://cloud-2.steampowered.com/ugc/578984310244785638/C3579187D0BCDE04639BCB6C005880C66CE7D919/).
I understand this may be a hardware fault, however, what is the easiest way to check this? I do not have a working spare GPU to test.