iMac (late 2013) EFI Update is recommended for iMac (late 2013) models.
trusted DOWNLOAD 8.3 MB FreeiMac (late 2013) EFI Update is recommended for iMac (late 2013) models. This update addresses an issue which may cause a black screen to appear when installing Windows 7 or Windows 8 using Boot Camp Assistant if both an external optical drive and USB thumb drive are connected to the system.
This software was checked for viruses and was found to be clean. Click here to see antivirus report.
This update does NOT apply to my iMac and has the potential to fry it, so I think a little more work on this app is needed before you damage someones pride and joy!!