The system fails to boot but I have no idea why Boot with the flag -v and carefully watch to determine at which point the system stalls and eventually fails System hangs at “PCI Configuration Began” If this happens then you should try installing the patched kext IOPCIFamily.kext. You can download this here . Make sure to read the Readme file supplied with package. My screen goes black (or grey) at boot Open the file org.chameleon.Boot.plist (found in /Extra of your USB disk or harddrive) in a text editor. Change: GraphicsEnabler=Yes to GraphicsEnabler=No (or the other way around) Save Reboot and try again Incorrect processor or memory speed is displayed. More than likely this is completely cosmetic, but it can be changed by using an appropriate /Extra/smbios.plist or editing one yourself. My audio/USB/Ethernet was working but I updated OSX and now it’s not This is a very common issue. Usually this doesn’t take too long. If you’re in a hurry to upgrade you can search the forum for...