On the clock speed it's x 2 which gives you the 1600. As far as safely overclocking you just need to up the gpu and memory in small amounts and test it. Rarely will you get the same results as other people. Use MSI Afterburner to overclock your card. You may get a good overclock and you may just get a small overclock on your card. My video card has certain issues with certain games when it's at a certain overclock so I just have to remember to change the profile when I play that certain game. You can use the MSI Kombuster to stress test your overclock.