I have a similar setup as you. I have a
PC: HP Pavilion Elite HPE-210f
CPU: AMD Phenom II X4 945
Chipset: AMD 785G
Motherboard: H-RS880-uATX (Aloe) turns out the manufacturer is Foxconn
Graphics: Nvidia GTX 560 Ti
Audio: integrated Realtec ALC888S
I have two monitors hooked up to the graphics card. My primary via HDMI and my smaller secondary via DVI port (with an adapter that turns it into DB9, old monitor). I read that there would probably be issues with the HDMI port so I disconnected it and installed Niresh 10.9 with my secondary monitor on DVI. I installed with just "amd64 -v" as my boot flags. It took me a few installs to try some things out, but this seemed to work best. I didn't mess with anything in the Customize menu during disk setup. Once the OS loaded and permissions finished up I was able to reboot. I was able to get back to the OS is I booted into safe mode using -x, but everything was slow including startup. I finally narrowed it down to just typing in "GraphicsEnabler=Yes -v" and everything booted up and I had working ethernet, Audio, video. Mac store and iMessage works. I haven't gotten iCloud to connect yet.
So maybe if you try something similar to what I did you will find success.
I do have one other problem if anyone can help me. When I plug my primary monitor into the HDMI port it makes my second monitor (which I installed with) turn off and the HDMI video doesn't get to my second monitor. Any idea why that is? Maybe there is something I need to do in OS that I am ignorant of or maybe it is a setup issue. Or maybe I have to reset video resolution. I don't need Audio thru HDMI, just video and both monitors will have different resolutions.
My org.chameleon.Boot.plist looks like this:
<?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">