I am looking for help with overclocking the crap out of my reference 7970 HD. Right now, it's running pretty stable at 1125/1575 on 1.112V (stock voltage). I am looking to get a maximum possible overclock with it, but keep it running in acceptable temperatures. I am not looking to buy any water cooling or aftermarket air cooler, I will keep it in reference design.
If I won't be able to overclock it to the good speeds, I will just sell it and get some aftermarket 680 GTX.
What is the best way to overclock 7970? In what increments should I be increasing voltage and frequencies? What program are best for testing overclocking stability of GPUs?
Blade's response is pretty spot on, but I'd like to add. Start with the core clock and memory; once they've both reached peak then adjust your voltage. But also make sure you slide your power ratio all the way. Once you've done that you can start overclocking further. To save you the hassle, 1.3 mV is usually the safest voltage before people run into driver related issues.
You may want to try 1250 to 1330 core clock; 1600 to 1875 memory clock at the 1.3 mV range. That should give you a solid overclock with relatively low temperatures. Anything above those, will require fine tuning like Blade stated.