Instead, macOS Sierra adds new features to the operating system, including the incorporation of Siri, expansion of Bluetooth and Wi-Fi-based connectivity features, and a whole new file system that replaces the venerable but outdated HFS+ system that Macs have used for the last 30 years.
Mac Support List
When an operating system encompasses such a wide range of new features and capabilities, not all older hardware is going to be able to upgrade. In this case, the list of Macs that can support macOS Sierra was trimmed substantially. For the first time in five years, Apple removed Mac models from the list of supported devices for a Mac OS. The following Macs are capable of running macOS Sierra:
Other Requirements for macOS Sierra
Apple didn’t issue specific minimum requirements beyond the list of supported Macs, but it does require that a machine run OS X Lion (10.7) and later. However, going through the support list and looking at what a base install of the macOS Sierra preview needs gives a good idea of the macOS Sierra minimum requirements, as well as a list of preferred requirements.
