Its displaying typical CPU bottleneck behavior. though a 3570k really shouldn't be bottle-necking a card like that.
Try overclocking, if its a CPU bottleneck that will alleviate some of the problem. If you have an aftermarket cooler already, you can pretty much just set the CPU multiplier to 42 for an easy 4.2Ghz overclock. Much higher than that and you have to start manually tweaking voltages.