I have to run mine at 800 i tired all kinds of setting so the HW error stay very low if I go up to 825 its ok but for me to many HW errors, not much more in a speed increase, so at 800 my g-black stays at 25 to 27 , so I'm happy with that i don't need to OC any way and I don't use stock fans either for less noise, i think it runs cooler now or seems to  . I use BFG 5.2 i put in place of 5.1 it runs better for me . my hard errors sty at 7 to 10 % doing it how i do after 24 hours so I'm  ok with that to .  i honestly think these thing are like Zeus which i run a long side it, 10 % is the Sweet spot for zeus and these to it seems.



IF the Hard ware error jump up to high to fast just reboot it . if your using BFG you don't need to add a chip count it see it np . this is my setting with bfg 5.2 on there own PI s .

With my grindseed G -black
 
 bfgminer --scrypt -S all -o your pool info here  -u user -p password --set gridseed:clock=800 --failover-only


 With my  cyclone/Tx2

 bfgminer --scrypt -S all -o your pool info here  -u user -p password --set zus:chips=96 --set zus:clock=328 --failover-only

using  --queue 0 --scan-time 1 --expiry 1, doesn't seem to do anything .
 
I was tiring to figure out how to make minera work with P2Pool but i don't think it does right now. which i just learned how to auto load on my  PI at command line at start up . it took me many hours of looking and tiring to get minera to load the url it wouldn't so i reformatted a SD and did above for when i use the F2 Pool.


 same setting work the same in Minera with BFG 5.2, i put in place of 5.1 .

 i would for sure lower that to 825 or down for the G black like some one else said . speed should go up and be more stable and HW errors should drop down a lot . make sure all your blades are working I mean, make sure  AC or shares don't say zero  if it does say ZERO the board might be bad it will show as working under speed but the lite on the board will only flash red and never turn green.