Seems that the "pre-set" cg miner had the clock speed set too high at 975. Took it down to 900 and doing much better. May need to actually take it lower than that.
Even 900 is way too much unless your Gridseeds are volt-modded. Try 800, let it run for a few hours, then increase by 25 MHz until you see no more improvement and go back to the last best setting. I'm guessing you'll end up between 800 and 850.
I've got Minera running them on an RPi and first started with 900 to let it automatically settle down. That sucks. For a month back I start with and 775 and see them creeping up fast with much better results from the start.