Is there a way to overclock?

My GPU through BIOS? I saw PCI-E clock but I want to make sure I don't do anything wrong, Right now it is set at 100mhz. Will I have to do any voltage changes or anything? I just want to do a mild 5%-7% overclock. I just dont want to keep using Rivatuner every time I shut it on and off to change it, for it get's annoying.