Dual graphics technology defines when the integrated GPU of a central/accelerated processing unit can work in tandem with an add-in board. Together with Mantle, the tech can help games run really well even on low-end PCs.
According to Advanced Micro Devices, the Kaveri accelerated processing units can enter Dual Graphics mode when your system has a Radeon R7 or R9 add-in adapter installed.
The performance difference (percentage-wise) won't be very large on R9 cards, but the improvements gained by systems with, say, a Radeon R7 240 are substantial.
According to AMD's tests, the Radeon R7 240, alone, runs Bioshock: Infinite at 20.4 FPS (frames per second) and Tomb Raider at 19.4 FPS.
In a Kaveri system, though, Dual Graphics tech pools the GPU resources together and increases the FPS.
The rate goes to 40.2 in the former (95% faster) and 38.1 in the latter game (again, 95% faster). So if you build a Kaveri-based PC, it actually pays to fork up $80 / €80 more for a low-end video board.
Games aside, the Kaveri also promises better audio via TrueAudio technology, as well as smoother film playback thanks to Fluid Motion Video.
TrueAudio takes 2-channel audio sources and turns them into multi-directional. It also adds more real-time voices and channels, and even eliminates noise.
As for Fluid Motion Video, it uses an intelligent compute algorithm to interpolate frames during playback of Blu-Ray movies. So between Frame 1 and Frame 2, you can have Frame 1a and Frame 1b, preventing stutter and loss of perceived detail if, say, you're watching a rapid car chase scene or something along those lines.
Add to all this the Mantle technology and, thus, a threefold increase in game performance over DirectX (for Battlefield 4 and, more recently, Starswarm, demo version) and you're all set. Now we just have to see if any other game makers adopt the API.
Editor's Note: During the Q&A session following a phone conference I attended last week, AMD implied that both R9 and R7 cards were supported by Dual Graphics. Since then, though, there's been word on the net that only R7 boards with DDR3 work. I'll see if I can get to the bottom of this.