Overclocking is a simple scienece that is easy to do but hard to predict.
Nothing is a full all out given, though some overclocks are much easier to get than others.
It's basically you giving more juice to your hardwear to play with so it can run faster.
With a 780i you'll just have to hit the delet key when the system posts then go into the bios and tweak a few settings.
Here's a good guide that should be some help.
Just be sure to monitor your temps with speed fan and core temp, and check for stability with memtest and prime 95 :-)
http://www.evga.com/forums/tm.asp?m=222688&mpage=1&key