I'm trying 53:2:950 right now actually. I have fans on the heatsink side (the big silver one with no components) only right now. I didn't think 35c was too hot.
What concerns me is the high HW rate though. Over 10% seems more than most people are reporting.
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.