Fast Sync is just an alternate v-sync method, and you would select "fast" under the v-sync setting, rather than on or off. It's to improve the performance of v-sync though, and if you have v-sync disabled, then it's not going to improve latency over what you already have...
Wondering what is NVIDIA Fast Sync that eliminates screen tearing while keeping latency low. Here is how to enable NVIDIA Fast Sync on GeForce GTX Cards
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I believe your monitor may support FreeSync, so the option to enable G-Sync would only appear if you have FreeSync enabled in your monitor's settings, have your monitor connected using a DisplayPort cable, then an option should appear to activate it for the screen from within Nvidia's control panel. However, again, it's main purpose is to be a better-performing form of v-sync, and it's unlikely to improve performance over having that turned off, just eliminate screen tearing, and only when your frame rate is below your monitor's max refresh rate.
One thing I did notice when doing a quick search about that mouse is that a review mentions there being an additional 1-2ms of input latency at DPI settings of 2100 or above. I'm not sure that kind of latency would actually be perceptible, but it might be worth dropping the DPI setting to 2000 and seeing if that makes any difference.
More importantly, you might want to try turning off "improve pointer precision" if it's turned on in the mouse's settings, as that can mess with the accuracy of mouse movement. I think most games should ignore that setting and get raw input anyway though.