Yes, completely. What brand is your card? Just about every card, if not EVERY card, has a corresponding software (Like Zotac's FireStorm) that gives you desktop options to safely and effectively overclock a card. However, there's still limitations. Boosting the clock will make it work harder, and thus perform better, but will increase the temps. Every card has a basic cooling solution, and these solutions can usually handle a pretty modest amount of OCing before it requires something beefier. That's usually where the 'novice' stops. However, many people like to take off the store-bought cooling solutions and use water blocks, to more safely crank up the OC and get low temps all the same.
Case and point, yes you can.