Abstract: An integrated circuit such as a video controller may be provided with core logic circuitry using CMOS technology which may be operated at different supply voltages such as 3.3 or 5 Volts. At lower supply voltages, the CMOS circuitry may run slower. For a video controller, certain higher resolution, pixel depths, and refresh rates may require high speed operation of the video controller. A monitoring circuit monitors the video mode, pixel resolution, pixel depth, and refresh rate and determines which supply voltage may be used to operate the video controller at such levels. An output signal from the monitoring circuit may be used by a switching circuit to supply an appropriate supply voltage to the integrated circuit. At lower performance levels, the integrated circuit may be operated at lower voltages to conserve power.