ASUS has released an update of its graphics card overclocking utility, GPU Tweak. Like MSI Afterburner, GPU Tweak can be used with any graphics card on the market.
ASUS has also uploaded a guide for overclocking a Radeon HD7970:
On my system, I have a GTX 460 (primary card) and a GT 520. GPU Tweak allows to monitor both cards but on the main GPU Tweak panel, only the tuning of the GTX 460 is possible. I didn’t find the way to change the clock speeds of the GT 520:
Primary card: GeForce GTX 460
Secondary card: GeForce GT 520