I have one of these as well, purchased in the last week, initially it was fine but after dropping on the latest drivers I started noticing a strange flicker. After logging in, as the screen fades to black, the entire screen wobbles left to right, then goes blank and then shows the desktop. The same thing happens if I go into CCC and adjust the gamma settings, everytime I modify the gamma up or down the entire screen shifts left and right very quickly. I'm yet to try the powercolor drivers but I will and cross my fingers.
Didn't touch the drivers nothing, changed my cable from a HDMI - to - DVI(HDMI from the video card to DVI into the monitor) works a treat, no more flickering. Might leave it like this until new drivers are posted from ATI.