Post Installation GPU and Audio problem with macOS Sierra

Hi guys , Just installed macOS Sierra following Tony Mac x86's guide and I'm having post installation issues. The problem is animations in MacOS Sierra lags and "About This Mac" shows GPU as Nvidia chip model 3MB. I'm using VGA port on my card. Does it matter? macOS Sierra also doesn't detect any audio output device despite installing Realtec ALC888b legacy / Realtec ALC888b / Realtec ALC888 legacy / Realtec ALC888 drivers via multiboot. How can I fix it? Thanks in advance. System Config : Processor : Intel Core i3 540 @ 3.06Ghz RAM: 8GB 1333MHz DDR3 Graphics card: Nvidia GTX 650 2GB Motherboard: Gigabyte H55m-S2 rev. 1.3 MacOS: macOS Sierra Version 10.12.6