Thanks for the tip Isokivi! I've deleted the file /live/image/BAMT/CONTROL/ACTIVE/noOCx and my Mem is now back to normal 175 Mhz speed. Other than that, are there some clocks I should try to get my performance up with minimal compromises?
Aggressive way:
I run mine and make sure they are stable at stock gpu speeds with mem underclock for a day or two. After that I try running at 800 MHz gpu clock. Out of 6 cards (12 cores) only two cores could not run 800 MHz (they run at 790 and 795 MHz just fine). My other 9 cores run between 800 and 855 at stock voltage... I have one "magic core" that is stable at 880MHz at stock voltage. If 800 MHz fails during the next day, i decrease that core(s) by 10 MHz, if it succeeds, I increase by 25 MHz, until they fail, then decrease by 10 MHz until they run stable. I recommend you do it while you have the ability to reboot the machine to minimize downtime. You can get pretty close to stable OC's in a few days with the only downtime being a few minutes while you reboot (if/when needed).
Safe way:
Increase clocks by 10 MHz and let run for a day... then repeat. Takes longer to find stable OC's, but allows for higher uptime, especially if you are not going to be near the rigs. I did all my rigs the aggressive way, but had to revert to the safe way on one of my rigs as one cards OC was causing others to lock and I would change the OC on the wrong card... isolated issue from what I hear, but the safe way helps eliminate issues like that.
I had stability issues with my mem at 175 on my 5970's, so I run at mem of 190... something to consider... I got all my OC's stable at 310 mem, then ran 190 for about a week... then tried 175 and had issues, so I moved it back to 190... not sure if thats just card specific or what... but I didn't spend much time on it as the difference is negligible at that low of speeds anyways.
Also, earlier in this thread is a post by lodcrappo about OC'ing eating into your profits, you might want to go read that as he has some numbers about how much ROI you get for overclocking and hours of downtime don't make up for a small overclock increase... Its a good thing to read and consider while you are looking for stable clocks.
I run everything with air cooling and no overvolting, so YMMV depending on your setup.