Radeon HD 8400 is an integrated graphics card on some of the Kabini APUs.
It is based on the Graphics Core Next Architecture and shares the main system memory of up to 800MHz, on a 128-bit memory interface, whereas the memory bandwidth and performance will depend heavily on the laptop configuration.
The codenamed Kalindi Core offers 128 Shader Processing Units, 8 TMUs and 4 ROPs.
Assuming the best combination possible, expect performance similar to an Intel HD 4000 and never below an Intel HD 3000. Thus, the card is only suited for modest 3D games and titles like BF4, AC4 and CoD: Ghosts are unplayable.