3D acceleration : it seems to "work" according the system, but the performance is very low compared to Windows, and the load on one CPU Core (used by Compton (0.1~beta2)) when graphics used, example a window moved on the desktop) is high. Same thing with the game "Scorched 3D" : 3D hardware seems "enabled" but is not used.

HDMI output issue : only the "external monitor" mode is possible (not the "clone mode" nor the "dual screen"). On the boot the display is OK on VGA + HDMI, but later on the GRUB menu only the HDMI work while VGA will go in sleep mode forever.

lspci -vmmnn

Slot:	00:01.0
Class:	VGA compatible controller [0300]
Vendor:	Advanced Micro Devices, Inc. [AMD/ATI] [1002]
Device:	Kabini [Radeon HD 8400 / R3 Series] [9830]
SVendor:	ASUSTeK Computer Inc. [1043]
SDevice:	Kabini [Radeon HD 8400 / R3 Series] [8623]

lspci -nnk

00:01.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Kabini [Radeon HD 8400 / R3 Series] [1002:9830]
	Subsystem: ASUSTeK Computer Inc. Kabini [Radeon HD 8400 / R3 Series] [1043:8623]
	Kernel modules: radeon