Usually when your 3D graphics start to show artifacts such as white dots ('snow'), you should back down 25 MHz and leave it at that.

More advanced users push the frequency often way higher. Example: If your card runs at 1000 MHz (which is pretty common these days) then I suggest that you don't increase the frequency any higher than 30 to 50 MHz. I always tend to recommend to novice users and beginners, to not increase the frequency any higher than 5% on the core and memory clock. It sounds hard, but it can really be done in less than a few minutes. Overclocking: By increasing the frequency of the videocard's memory and GPU, we can make the videocard increase its calculation clock cycles per second. We can really recommend it, download here. One of the best tools for overclocking Nvidia and AMD videocards is our own AfterBurner which will work with 90% of the graphics cards out there. Typically you can tweak on core clock frequencies and voltages. As most of you know, with most video cards you can apply a simple series of tricks to boost the overall performance a little.

Overclock gtx 960