Developers have created workarounds to install macOS Sierra on some Mac computers that are no longer officially supported as long as they are packed with a CPU that supports SSE4.1. Sierra is the first version of macOS since OS X Mountain Lion, released in 2012, that does not run on all computers that the previous version supported. MacBook and MacBook 12-inch: Late 2009 or newer.MacOS Sierra requires at least 2 GB of RAM and 8 GB of storage space and will run on: 2.2.7 Other applications found on macOS 10.12 Sierra.