Hi, I read your thread and realized that I have a very similar model and specs as to what you have. So I've decided to give it a shot. And yes, I was able to install El Capitan on this machine.
My specs,
-MODEL ACER AM5630-U5202A
-MOBO: EG31M V1.0
-CPU: Q6600 (Originally came with E4500, but i swapped it with q6600)
-GPU: NVIDIA 9500GT (Originally had ATI 2400 PRO)
-MEMORY: 3GB 667MHZ
-STORAGE: WD 160 GB HDD
I followed these steps
Bios Settings
-Update Bios to latest version
-Load to Default Settings
-Disabled Onboard IDE Controller
-Enhanced Onboard Sata Controller
Unibeast settings
-Unibeast 6.2.0
-Legacy Boot Mode
-El Capitan
-Inject Nvidia or AMD (for your case)
On an initial try, i ran into a stop sign during installation process. But after using a different usb port (used onboard usb port), boom, I was able to complete the installation. couple of things though, for post installation, I could not install FakeSMC and Audio KEXT using multibeast and had to install FakeSMC manully.
