Using a Ryzen 5 1400 system with the Gigabyte AORUS AX370-Gaming K7 motherboard and G.Skill Trident Z DDR4 memory, he's the first overclocker to break the 4GHz DDR4 mark on the Ryzen platform.
His single memory stick was overclocked to 4079.2MHz effective. The Ryzen 5 1400 processor on the other hand was underclocked to just 815.85MHz.
For reference, the best DDR4 speed achieved on the Intel platform is 5500MHz.