Sorry for the late reply, I just started messing with my Hackintosh again last night. I'm now up and running with full res and acceleration on 10.9.4 with the 8800GT using an 8800GT EVGA bios.
Now what has actually made it work I'm not sure, it seems so hit and miss its unreal. Every time I've formatted the system I get different results, even when the process has been identical to the previous attempt. The bios the graphics card is using does seem to make a difference. At one point I didnt touch the OSX86 install at all and just flashed the graphics card with different bios images and rebooted to see what osx would do. Sometimes it was the black screen, sometimes it would start up identifying the card, sometimes it would start without identifying the card.
In the end this is where I got to.
1. Install Niresh 10.9 on my main drive (I called it Mac HD), removing the Nvidia drivers during the install or after install with 'grafix backup all'
2. Install Niresh 10.9 again on a second drive and called it Mac Recovery.
3. Update to 10.9.4 - Because I was getting issues running some installers I would boot from the Mac Recovery drive and run the OSX 10.9.4 Combo installer and choosing to install to 'Mac HD'. Every installer I have tried has been happy to install as long as I wasn't booting up from the drive I was installing to (strange).
4. I tried manually adding an EFI string for the graphics card, when the card was using the FX3700 bios and when using an 8800GT bios. This gave me the same results as using GraphicsEnabler=YES. This is what I expected, as far as I'm aware the GE=YES option just injects the graphics card info as using an EFI string does. In the end I used an EVGA 8800GT bios and removed my EFI string. Using only GraphicsEnabler=YES.
5. Here was where things changed a bit. After using the EVGA bios I wasnt getting a black screen any more, no matter what drivers I tried the system would start up but with no acceleration. Then I installed the NVDA4ALL v2.3 for 10.9.4, the system started but with no acceleration. The NVDAStartup.kext would load but no driver for the card would load. This was the first time I saw NVDAStartup load. So then I installed the official Nvidia web driver for 10.9.4 without removing the NVDA4ALL kexts. The system then started up with full res and acceleration . WTF???
Now the Nvidia Manager works but only for the first user I created on the system, other users get an error message when trying to open the Nvidia applet. The reason I started messing with the graphics card bios in the first place was because after looking at the nvidia website at the supported cards for the 10.9.4 driver I saw that the 8800GT was listed as supported but not the FX3700. Previously I had more success with the card running as a Quadro FX3700 (they are both G92 cores).
So far I can see little logical reason to why sometimes it will work and sometimes it wont even though I was using the same software and methods every time. The only thing that has changed is the bios I used on the graphics card but that may not be the reason its running this time as I've had that card running correctly on 10.9.4 using the NVDA4ALL v2.3 driver in the past. That didnt work this time around lol.
Make yourself a bootable USB pen with the nvidia flash utility and try out some different bios images on it, see how you get on. Its also worth having a look at what bdmesg outputs, that will show what chameleon is doing at boot.