Some sort of energy saving feature? Try with power cord connected and change settings on energy saving on control panel or asus app
PS Vita and PC gamer
CPU Intel i5 2500K at 4.5 Ghz / Gigabyte Z68 Mobo / 8 Gb Corsair Vengeance 1600 mhz / Sapphire HD 7970 Dual X Boost / Corsair Obsidian 550d