I have my Asus 8400GS woking perfectly with these 3 things:
1) NV Enabler in Multi Beast.
2) I added the last line to the device ID in NVDANV50Hal.kext
<string>
0x00f010de&0xfff0ffff
0x019010de&0xfff0ffff
0x040010de&0xfff0ffff
0x042010de&0xfff0ffff
0x05e010de&0xfff8ffff
0x05f010de&0xfff0ffff
0x060010de&0xffe0ffff
0x062010de&0xffe0ffff
0x064010de&0xffe0ffff
0x06e010de&0xfff0ffff
0x086010de&0xffe0ffff
0x08a010de&0xffe0ffff
0x0a2010de&0xffa0ffff
0x0ca010de&0xffe0ffff
0x10c310de&0xfff0ffff
</string>
3) Here is my "com.apple.Boot.plist" in the "Extra" folder.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Kernel</key>
<string>mach_kernel</string>
<key>Kernel Flags</key>
<string>arch=x86_64</string>
<key>GraphicsEnabler</key>
<string>No</string>
<key>Timeout</key>
<string>1</string>
<key>Legacy Logo</key>
<string>Yes</string>
<key>EthernetBuiltIn</key>
<string>Yes</string>
</dict>
</plist>
------------------------------------------
I was concerned that Cinebench only gave me an Open GL score of 6.2.
So I ran it in Windows 64, and got 5.7.
I hope this helps.