asus boards do that. not a big deal at all. I promise it wasn't running at 0c either lol
58 at 30 minutes is HOT. That said, run it for 2 hours and make sure it stays under 70c.
I hate to be a negative nancy, but...
add cpu-nb to 1.25-1.3. If it doesnt stay stable then go with multiplier.
for my 8320, im running 1.4 cpu volts, and 1.25 cpu-nb and under clocking the ram to 1480 mhz from natural 1600mhz @ 4.51 ghz