if the difference between standard and auto overclock is not too much for speed and voltage, it would be safe alone. but if too much of the stock then it could endanger the system and hardware. Just suggestion
No. As long as you stay within Intel's max voltage (1.45 volts) and max temps (about 70 C), there's no danger.
But it is simpler to just run with SpeedStep enabled. For example, I have my Q9550 (EP-45-UD3P) running at 3.6 GHz (B3 stepping ). That's 425 MHz X 8.5. SpeedStep drops the speed back to 2.55 GHz whenever I am not gaming.
Same with my Q6600 system - 3.6 GHz down to 2.4 GHz.
I do not need to constantly go into the BIOS and change speeds.