Hi i am trying to install OS X El Capitan on iMac 2008 model Core 2 Duo processor, and 4GB Ram. The way i followed is i created a USB bootable stick and insert to mac machine and restarted the Machine then i pressed C key in keyboard and i waited more than 30 seconds then it is not showing any usb Bootable option and later it booted directly. Even i can`t able to Boot CD Drive also. can any one help me out here please.

  • Why can't you upgrade directly using the installer from the App Store? And which instructions did you follow to create the stick?
    – nohillside
    Oct 16, 2015 at 13:25
  • Why didn't you just put the 'Install El Capitan' app in the Applications folder & run it from there, as intended? [btw, it's not easy getting a Mac with a Superdrive to boot from USB]
    – Tetsujin
    Oct 16, 2015 at 13:25
  • @patrix iMac final update 10.5.8 only and App store not showing any update for iMac core 2 Duo machine Oct 16, 2015 at 16:58
  • @Tetsujin i directly tried that option but the app icon showing no valid symbol . Oct 16, 2015 at 17:01
  • Where did you get the installer app from?
    – nohillside
    Oct 16, 2015 at 17:29

3 Answers 3



  • Holding down Option at boot, not C. This will show every available boot option
  • Make sure you are using a USB keyboard attached directly to the machine

Holding CMD + C will not boot of an USB, only a DVD.

You need to hold the option key then select the USB Drive, which will be most-likely named EFI. Also make sure you aren’t plugging it in through any USB hubs and just directly into the computer.

Note: If your able to install El Captain on your computer, doesn’t mean it will run well. Because of its age it can possibly be very laggy and be very hard to use, personally I’d recommend at max using Yosemite.


Even though the Core 2 Duo is technically 64-bit, it won't run anything newer than Snow Leopard (10.6.8).

  • I have Lion 10.7 installed on my brother's 2016 Core 2 Duo black MacBook. It can also run current versions of Windows 10 and Linux Mint, albeit after some annoying technical rituals.
    – VizJS
    Aug 22, 2018 at 0:07

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