Unreal Tournament 3 was tested using maximum image quality settings with AA/AF disabled and at 1024x768 and 1920x1200 resolutions. Even at 1920x1200 we noticed a slight performance difference between the processors, with the Core i5 661 trailing behind the Core i5 750 and Phenom II X4 945 processors by just 2fps. At 1024x768 the margins were larger, and here the Core i5 661 was 13% slower than the Core i5 750, and 6% slower than the Phenom II X4 945.
The Core i5 661 performed well in Street Fighter IV, delivering the best result at 1920x1200 with 184fps. Then at 1024x768 the Core i5 661 matched the Core i5 750 with 236fps, making it 13% faster than the Phenom II X4 945.
The last game we tested with was Far Cry 2. At 1920x1200 the Core i5 661 does very well with an average of 70fps. At 1024x768 the story was a little different, as the Core i5 661 was slightly slower than the Phenom II X4 945, and falling 15fps behind the Core i5 750.