How to fix Hackintosh Grey/Black/White Screen & No Signal Problem in Hackintosh Installation

This often happens to Hackintosh beginners because of incompatible Graphics card / Graphics chipset
After successful Installation or Upgrade you may see grey screen, or your monitor may turn off (black screen) with No Signal (sleep mode)

Incase if your issue is related to nVidia web driver view web driver post

This can be fixed by Removing (Backing up The graphics kexts) which will trigger VESA Graphics (No Graphics Acceleration)
You can Install the graphics kexts later

You should boot OS X in Safe mode to start the process
use the boot-flag -s to boot in Single User Mode (In Clover Bootloader Press Space Key)
You Will see a screen like the following image

Now you’re in single user mode
enter these commands (one command at a time then press enter)

fsck -fy
mount -uw /

Now its time to make backup of Graphics Kexts

Case 1

if you are using Niresh 10.8.5 distro, 10.9.0 distro or any latest Niresh version you can simply backup all the kexts using the following command, otherwise go to case 2

grafix backup all

This command will backup all the graphics kext to a folder (Backup) in root
so after this you can reboot using reboot command
reboot
at the end you can login without QE/CI Acceleration
Before trying any Patched kexts or Packages Make sure to Install The Backup Kexts

Case 2

So you have to backup your kexts manually
enter the following commands one by one

mkdir /Backup
cd /System/Library/Extensions
mv -Rf NVD*.kext /Backup
mv -Rf ATI*.kext /Backup
mv -Rf AppleIntelGMA* AppleIntelHD* AppleIntelSNB* AppleIntelIntegratedFramebuffer* /Backup
kextcache -i /
reboot

The above commands are intend to create a Backup folder then backup
all Intel, nVidia & ATI Kexts to that folder
at the end of it restart the system
at the end you can login without QE/CI Acceleration
Before trying any Patched kexts or Packages Make sure to Install The Backup Kexts