OS X El Capitan system requirements
If your Mac was able to run Mavericks or Yosemite it will be able to run El Capitan. Those supported Macs include:
iMac (Mid 2007 or newer)
MacBook Air (Late 2008 or newer)
MacBook (Late 2008 Aluminum, or Early 2009 or newer)
Mac mini (Early 2009 or newer)
MacBook Pro (Mid/Late 2007 or newer)
Mac Pro (Early 2008 or newer)
Xserve (Early 2009)
All of those Macs feature a 64-bit CPU. You’ll also need about 6GB of space to be available for the install (so make sure you have more room than that or you may encounter issues).
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