This requires using a patch to modify the install image. 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. MacOS Sierra requires at least 2 GB of RAM and 8 GB of storage space and will run on:
2.1.2 iCloud Drive and Optimized Storage.