Curious to know if your current Mac will run macOS Sierra when it's released later this year?
See also: Will your iPhone or iPad run iOS 10?
Just because it can run Mac OS X 10.11 El Capitan doesn't mean it can run Apple's latest operating system.
According to the information made available at the WWDC 2016 keynote, here is a list of the Macs that will be supported:
El Capitan supported some Macs going as far back as mid 2007.
Support for all Xserve systems has also been dropped in macOS Sierra.