It's like this on my laptop, with same settings as my stationary rig, which looks perfect, so could be a hardware issue. It has an AMD Athlon X2 card.
Specs: intel i5 3570k @ 3.4GHz;
16Gb RAM; Raedon HD 7900;
Win8 64-Bit
16Gb RAM; Raedon HD 7900;
Win8 64-Bit
