I have the same specs as you (except 2 more GB RAM) and I run mostly fullspeed in Dolphin IL (slower in the city). Not sure if RAM is that important to Dolphin or else you should get the same.
Specs: intel i5 3570k @ 3.4GHz;
16Gb RAM; Raedon HD 7900;
Win8 64-Bit
16Gb RAM; Raedon HD 7900;
Win8 64-Bit
