this might be a topic better for the Overclockers Anonymous forum...
but in short, your ati catalyst driver should have some basic overclock setting built into it for the graphics cards.
i'm not totally sure that the 970 has an unlocked multiplier... if it does not, then you just have to turn up the b-clock setting in your bios from 133 to higher. best to do this in small increments, as you don't want to blast it up to 200 all at once and blow your cpu.
overclocking is an art, so read up, and ask lots of questions... check out the Overclockers Anonymous forum for more info.
my main rig...
asrock 970 extreme3
AMD athlonII X3 440
zalman cpns5x performa hs/fan
crucial ballistix 2x4gb sport ddr3-1333
powercolor ax7750 1GBK3-H vga
antec neo he 650r
Samsung 840 EVo SSD 120 GB
toshiba 2TB HDD 64M cache sata3
seagate 1TB HDD 64M cache sata3
hitachi 2TB HDD 64M cache sata3
lg wh14ns40 bd burner
optiarc ad-7240s sata dvdrw (nec chipset)