The System Management Controller (SMC) a low-level system on your Mac that controls power to system components. The SMC interacts with components such as the fans, display and keyboard backlights, power button responsiveness, and the graphics card.
Corruption of the SMC may occur due to bad software updates, power surges, and overheating. Resetting the SMC will reset the voltage to your graphics card.
To learn more about how to reset the SMC for your specific Mac, see Apple's official SMC Reset page.