I have 5 of
Gigabyte AMD Radeon HD 7970 OC 3GB GDDR5 DVI-I/HDMI/2x Mini-Displayport PCI-E 3.0 Graphics Card GV-R797OC-3GD
690-700Mhash per card
I just bought one of these to start mining (yes, bad time, I know) how do you get your hash rate up there? I'm at about 600Mhash (give or take) doing nothing outside of the defaults with GUIMiner.
I'm a little nervous about changing the overclocking settings because I don't want to fry my board, but if someone can give me any specific guidance it would be helpful.
OT: If I don't make all my money back on this card mining, it's okay, I might switch to litecoin mining after ASIC's start shipping if the return looks good, or maybe even do folding@home instead...
Edited later on tonite: I tried to launch the AMD/ATI Catalyst utility (win8 64 bit) to poke around and it wouldn't launch. Un-installed it, deleted the folders, reinstalled it, reinstalled the version from the AMD website for win8, (as opposed to the version provided by Gigabyte for Win 7 and Vista) and so on, nothing works. This has been documented a variety of places with a variety of solutions, I tried a bunch of stuff, but if that's the way I have to do it I may have to re-install Windows 8. Not that big a deal since I don't do anything else on the PC, but *this* is why I don't use Windows anymore for personal use...
I own the card that you bought. Nobody really uses Catalyst to overclock... I would use MSI Afterburner. Bump your core clocks up by about 10-20MHz, then mine for a few hours. If your computer doesn't crash, you can up the clocks by another 10-20MHz again. When it finally does crash, bring your core clock back to the previous setting it was stable at. On that card, you can't adjust the voltage so you won't be able to get any crazy overclocks. This is okay though, because you tend to use a lot more power when you overvolt. Also, don't worry about cooling for this card. You will be able to monitor your temperatures in afterburner. If you have your fans on the auto setting, your card should stay at around 63 degrees C.
Another thing you should do is take the memory clock down to 900MHz. This is the lowest you can go. The reason why you do this is to save electricity. You don't use the memory of the card when you're mining. Just remember to up it back to what it was originally before you play a game or something.