How to reinstall El Capitan?

Discussion in 'OS X El Capitan (10.11)' started by bcodemz, Mar 8, 2016.

  1. bcodemz macrumors member

    May 6, 2014
    I currently have a 13'' rMBP and it is running almost uselessly slow. I just got a 15'' rMBP, and the speed difference is literally night and day. I need to do something, because my rMBP was never this slow.

    How do I reinstall El Capitan?
  2. Bunnychick macrumors newbie


    Mar 8, 2016

    Please make sure you back up your data and any applications you will need to reinstall. Then boot into recovery mode by holding the "command+R" and press the power button. From within recovery mode you can erase your drive and reinstall to give you a clean slate.

    You will need to be connected to the internet and make sure you have your power adapter as well since this can take a while depending on your internet connection speed.

  3. simon lefisch macrumors 6502a

    simon lefisch

    Sep 29, 2014
    Download El Cap from the App Store and create a USB installer (some people like to use Diskmaker X, I prefer using Terminal)

    Restart your MBP and hold Option.

    Select the USB installer drive.

    From there you can wipe your drive and reinstall El Capitan.

    No need to use Internet recovery. Make sure you backup all your data in TM before reinstalling.
  4. kagharaht macrumors 6502a

    Oct 7, 2007
    The problem is that when you restore from Time Machine, you are just reinstalling all the issues back. What good is reinstall from Time Machine when it just brings back the problems again.
  5. BLUEDOG314 macrumors 6502


    Dec 12, 2015
    If you use time machine to do a reinstall, yes, it brings back all the system files. What I do is tell time machine to only back up folders such as documents, and stuff that holds media files and what not. Everything else I do clean installs for. That includes the OS, and any programs I use. I'd rather install the most up to date version than hope migration assistant can make everything work again.
  6. simon lefisch macrumors 6502a

    simon lefisch

    Sep 29, 2014
    No one said anything about restoring the entire OS from TM. If anything gets restored it's user data (docs/apps/etc).

    The only reason you would restore the entire OS is if there is a major prob that causes the new install to be unusable. Then restoring the previous OS backup at least gives you a working image, even if it is slow.
  7. NoBoMac macrumors 68000

    Jul 1, 2014
    I'm agreeing with kagharaht and BLUEDOG314. Pulling the old stuff back over a new install might just re-introduce the real problem.

    Clean install is such an old school Windows things to do (not that it might not fix the issue, but I have a 2008 MBP running well and only once re-installed clean: when I put in a SSD), but if going to do that, will want to re-inntroduce old/original items piecemeal. In other words, make sure the clean install is running well before re-installing things, otherwise you're back to square one.

    First things first. Are both the machines configured the same re: software? Same programs installed and running? Same Safari/browser plugins/extensions (eg. I once had an ad blocker extension that caused serious performance issues)? Have you brought up Activity Monitor to see what processes might be consuming large amounts of CPU, and what about memory pressure?
  8. CoastalOR macrumors 68020


    Jan 19, 2015
    Oregon, USA
    Here is Apple Support on "How to reinstall OS X on your Mac". The instructions will work for El Capitan.

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