When a user engaged 3D mode, the GPU would render two separate, offset images (one for the left eye and one for the right). The Controller Driver would then synchronize the refresh rate of the monitor with the infrared emitter. The emitter would signal the active shutter glasses to alternately darken the left and right lenses in perfect sync with the monitor's refresh cycles. Without the specific Controller Driver, the emitter would not function, and the glasses would remain inert, rendering the expensive 3D hardware useless.