I found the solution !
Edit NVDANV50Hal.kext and in IOPCIPrimaryMatch key, add device id 0x10c310de
Moreover edit nvidia.c and add { 0x10DE10C3, "GeForce 8400 GS" }
It works fully : HDMI, DVI, VGA, QE, CI, Resolution in Pref panel ...
And there is an audio chip in this video card for HDMI...