Get the cmd line frequency setting as low as possible, it ensures maximum time by GPUs crunching WUs. Dont set it to zero, wierdness will ensue, otherwise pretty much set it to as low as you can get away with.

The screen slow down this can cause is not really an issue with 7970s, as they switch so fast to screen servicing and do it in a flash, so dont need the time set for extended time servicing the screen - set low as she will go, and leave it there. I would anticipate the new NVidia range to do that as well, its more a function of 28nm cards enabling fatser technologies than card Vendor.

The lower it goes, the more heat is chucked out (its doing more work crunching), so watch temps as they will increase from the norm when the frequency statement is not used.

Preferences that dont clash with app_info (cant think of one that does, although as always there is probably a small exception somewhere), will operate as normal.

Regards
Zy