Have you been having problems with the HDMI connection on your new Mac mini? You’re not alone. Apple has released a firmware update for all 2012 Mac mini owners that addresses a “HDMI video flicker issue.” The issue seemed to be originally related to an Intel driver, but it has been fixed now that Apple has issued an official firmware patch.
The update is available now in the Mac App Store.
Your Mac mini’s EFI firmware will update to version 1.7. The download is less than 5MB and is also available on Apple’s support site.
Source: Apple