Hybrid CrossFireX is the equivalent of NVIDIA’s GeForce Boost technology. It is targeted to low-end systems with on-board video motherboards. When you install a “real” video card compatible with this technology, the system sets the video card and the on-board video to work in parallel in CrossFire mode, increasing gaming performance.
Like it happens with NVIDIA’s counterpart, you need to have a motherboard with a compatible chipset and also a video card that supports this technology in order to use it. So far only motherboards based on AMD 780G chipset and video cards based on Radeon HD 2400 and Radeon HD 3400 series are compatible with Hybrid CrossFireX. This technology only works under Windows Vista.