People have had similar problems before. It's likely that the board doesn't supply stable power to an 8 core 125W TDP FX chip, hence why it's no longer listed in ASRock's own support list. Since it's not listed there, I wouldn't use it.
Here are a list of motherboards that I would feel comfortable using an FX 83xx with:
ASUS M5A97 R2.0
Gigabyte GA-970A-UD3
Gigabyte GA-970A-UD3P
ASUS M5A99X
Gigabyte GA-990FXA-UD3
Gigabyte GA-990FXA-UD5
Gigabyte GA-990FXA-UD7
ASUS Sabertooth 990FX
ASUS Crosshair V Formula Z
Honestly, a GA-970A would be just fine. It has 8+2 power phases which is stable enough for the chip. You could even do some overclocking if you'd like.