I am trying to overclock my msi gtx 660 from 980 MHz to 1280 MHz in 100 MHz leaps. I am using gpuZ, msi afterburner, msi kombuster, and fraps to benchmark my graphics card in far cry 3. When i first tested my card at 1080 MHz, it benchmarked slightly worse than at stock, and I have no idea why. I ran the benchmarks twice at both 980 and 1080 MHz in the same areas and consistently get around 45 fps. After running the benchmarks the game randomly crashed, which never happened to me before. What I am wondering is if a 100 MHz increase is too small to make a noticeable difference in a game or do i also need to increase the voltage? Also will a 100 MHz overclock make a card unstable without increasing the voltage? Should I take smaller steps or larger ones?