I have heard allot of people talking about some program for AMD based cards to overclock. I just got a 7870 Tahiti Le and it works better than I had thought but I don't think I got any OC program with it . I don't need to yet but it would be nice to be able to OC if needed. Plus I was wondering if there is a way to manually set your fan speed for both GPU and CPU cooler or a GPU OC/fan controller in one program would be the beez neez.
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You can use CCC (Catalyst Control Centre) which you can download from AMD (including the newest drivers).
MSI Afterburner is another alternative.
Asus GPU Tweak is useful too.
Go for MSI afterburner. It is the best overclocking tool for AMD cards