The video card works well with the Nouveau driver with 3D acceleration.

In Trisquel 4.5 you can play videos smoothly at full screen. Video effects work.

Revision 02 works.

lspci -vmmnn

Slot:	05:00.0
Class:	VGA compatible controller [0300]
Vendor:	NVIDIA Corporation [10de]
Device:	G86 [GeForce 8400M GS] [0427]
SVendor:	Hewlett-Packard Company [103c]
SDevice:	Device [30cf]
Rev:	a1

lspci -nnk

05:00.0 VGA compatible controller [0300]: NVIDIA Corporation G86 [GeForce 8400M GS] [10de:0427] (rev a1)
	Subsystem: Hewlett-Packard Company Device [103c:30cf]
	Kernel driver in use: nouveau
	Kernel modules: nouveau, nvidiafb

lspci]

01:00.0 VGA compatible controller: NVIDIA Corporation G86M [GeForce 8400M GS] (rev a1)

lspci -nnpk

01:00.0 VGA compatible controller [0300]: NVIDIA Corporation G86M [GeForce 8400M GS] [10de:0427] (rev a1)