Intel processor from 1.1V to 4.2 GHz, built for the Ryzen 5 3600 chipset.
I've noticed the highest I've seen is 3890 on 4.2, though it's usually near 3700.
I attempted 1.35V at 4.5 GHz, but temperatures rose to about 77-80°C. At 4.2 GHz it stays under 65°C, though I mostly run my CPU there.