I was run Dota 2 and Path of Exile, then I went to check my HWMonitor and it shows the CPU peak voltage is 1.303V. I'm very worry now, is this voltage any harmful?
1.3v was the recommendation for older 22nm CPUs, which had much lower stock voltages. Plenty of Skylake CPUs come from the factory running higher than 1.3v.
The single-core boost voltage will be a little higher than the multi-core boost voltage. I doubt there is anything to actually worry about here unless you messed around with core voltage tweaks.
I've searched around and seen some people advice that the voltage when not overclock should not pass 1.3 so I worried because of my 1.303 V. Maybe HWMonitor wrong, now I'm using Intel XTU to recheck again.
1.3v was the recommendation for older 22nm CPUs, which had much lower stock voltages. Plenty of Skylake CPUs come from the factory running higher than 1.3v.