yeah...biostar is quite horrible, they're like the modern ECS (if anyone gets the reference). Their BIOS are all terrible. I've got friends who went on the cheap and got Biostar and they all regret, those boards can't overclock properly and don't have sufficient power phasing.
Also your overclock is quite crazy, 1.4375v is really high for a 4.6ghz overclock. You should be towards 1.4v which that will lower that temp to around mid 40's and maybe high 30's. Also check the temperature for the NB and SB and make sure they're not hitting in the 50's because that might be the reason why its now allowing higher clock ratio. Overclocking the bus itself may raise voltage for the NB, CPU/NB, and SB if you have it set on Auto. I would try overclocking CPU only with multipliers and see if that solves the issue. With my Gigabyte 990FXA-UD3 i had an issue where if i raise the bus higher than 225mhz i would get throttling from the CPU/NB and then my clocks weren't stable.