Installing El Capitan on a computer with Yosemite

[Asturar]

If my Havkintosh already has Yosemite on it, can I just upgrade to capitan through the App Store screen?

 

[birdmann]

Unfortunately no. You will have to install El Capitan from a USB pendrive just like you would if you were starting from scratch. I did this recently coming from Mavericks to El Capitan and my suggestion is that you create a partition on your hard drive and clone your Yosemite partition onto your new partition, this way you have a backup in case anything goes wrong during your install. Then install El Capitan from your Unibeast pendrive onto one of the partitions containing Yosemite.

 

[cheetaa]

If your Yosemite system has got Clover installed, the answer is YES, you can upgrade it.

I did it without problems.

More info here:

Direct Update to OS X El Capitan Using Clover