While the Gridseed blades may have defaulted to 750 Mhz, that was actually a pretty strong overclock given the VERY WEAK power setup on those things.
Try dropping to 600Mhz or so and see if the problem continues.
Ran this at work and it crashed at around 3 hours after starting it. I checked the temps and they are just above room temp. What could this be. To power these things im using 2 12v 6amp chargers that fit. actually they are from my zeus blizzard miner that I retired when I got the blade.