You can overclock a GPU on any motherboard regardless of the chip set as long as the GPU is supported. I have OC'ed AMD 6 series cards on my old AM2 motherboard for example.
Just download a utility for overclocking such as this:http://event.msi.com/vga/afterburner/download.htm
You can overclock when you are booted into your OS.
Unlike CPU overclocking, GPU overclocking is mostly done via your OS and not your BIOS.
Also if you have not overclocked before, do it in small increments and increase your fan speeds at the same time. Use this to monitor your temperatures.http://download.cnet.com/SpeedFan/3000-2094_4-10067444.html
The 7 series are lovely for overclocking. I have a 7870 myself and am loving it. They do not heat up much and run very cool.
Let me know if you need anything else. Cheers mate. :-)