I'm trying 53:2:950 right now
Your board may need 950mV to get rid of most of those HW errors. You could also try int:53:2:850. I get lower a higher hash rate and lower HW errors (virtually none) on my boards with 54:2:850 than I do at default settings (40:1:850).

And definitely get another fan cooling the line regulator heatsink as well as those teeny little heatsinks, especially if you want to use 950mV.
I *am* using 950mV. I said so twice already. :-)
I tried int:53:2:850 earlier, the error rate was higher.
I'm using a large floor fan blowing over the whole board. Pretty sure it is cooling the whole board pretty well. Without a temperature sensor gun, is there a way to tell if components are getting hot and causing the HW errors?