Because this new card uses the 260's memory bus and memory effects dominate at higher resolutions with AA turned up? Because its core clock is the same as the 260? Yes, its cores have the same number of shaders as a 280, but if you run at 1920x1200 or above it's probably more like a pair of 260's in SLI than a pair of 280's - and there's no point in having a $500 card if you play on a crappy screen.