If you want to do a fresh install, you can create a USB install drive: http://arstechnica.com/apple/2014/10/how-to-make-your-own-bootable-os-x-10-10-yosemite-us

If you want to do a fresh install, you can create a USB install drive: http://arstechnica.com/apple/2014/10/how-to-make-your-own-bootable-os-x-10-10-yosemite-usb-install-drive/ http://arstechnica.com/apple/2014/10/how-to-make-your-own-bo...