Here you will find instructions for resetting or resetting NVRAM, PRAM and SMC on the Apple Mac or MacBook. Many problems that arise when using the Apple Mac can be solved by resetting these three things. Often there are also reader questions here on the blog, the answer to which lies in resetting NVRAM, PRAM and / or SMC. In addition to the instructions for Do It Yourself, I would also like to briefly explain the individual terms.
Update June 22, 2020: Instructions for the SMC reset on Mac and MacBook with T2 Security Chip (End of update)
Chapter in this post:
- 1 Brief explanation of terms: What are NVRAM, PRAM and SMC?
- 2 Instructions for NVRAM and PRAM Reset: Reset the Mac RAM
- 3 Are there any problems? Trouble shooting during NVRAM reset
- 4 Before we get to the System Management Controller Reset ...
- 5 Instructions for the SMC reset: reset the system management controller chip
- 6 signs the SMC may need to be reset
- 7 Any more questions?
- 8 Similar posts
A brief explanation of terms: What are NVRAM, PRAM and SMC?
Before we get to the reset of NVRAM, PRAM and SMC, let's first clarify the terms. Not every user knows what to do with NVRAM, PRAM and SMC and may therefore shy away from resetting them accordingly. So here is a brief explanation of the three abbreviations for you:
|NVRAM||"Non-volatile random access memory“, A non-volatile memory that comes close to RAM, but remains in place even without an external power supply. Unsegmented, hardly limited and non-overwriting memory - hence sometimes a "garbage cache".|
|PRAM||"Random Access Memory parameter“, A memory not dissimilar to NVRAM, but which mainly contains data from the operating system. Among other things, OS X or macOS stores data such as volume, font formation, alarm settings, monitor data, double-click intervals, the hard drive cache, etc. in the PRAM.|
|SMC||"System Management Controller“, A chip on the motherboard of the Mac or MacBook that controls voltage-dependent functions (also and above all of the hardware). Affected here are the fan, USB ports and USB devices, the Bluetooth module, etc. The SMC reset thus solves minor hardware problems and the associated system failures / overloads.|
Instructions for NVRAM and PRAM reset: Reset the Mac RAM
Only older Mac models have a PRAM, most newer devices only use NVRAM. Therefore there is only one guide for resetting NVRAM and PRAM. And this is how it works:
- Turn off your Mac or MacBook (if not already off)
- Turn on your Mac or MacBook
- Hold Command + Option (Alt) + P + R (⌘ + ⌥ + P + R) during system startup
- When the system starts to sound for the second time, release the buttons
- Then checks information such as the boot hard disk / boot partition, display and time or dates and other system settings; if necessary adjust them again to your preferences
There are problems? Trouble shooting during NVRAM reset
It can happen that when resetting the non-volatile random access memory or the parameter random access memory nothing happens and you only get a gray screen. Here it can help to unplug all USB or Thunderbolt devices. Take the peripherals off the Mac (except of course the keyboard, if it's wired) and switch off the Mac (if it doesn't catch itself and remain in its gray shock). Then repeat the above procedure.
Before we get to the System Management Controller Reset ...
Apple thinks that if you have system problems, i.e. if the hardware is crazy, you shouldn't reset the SMC first. Rather, one should end problematic tasks, restart the computer and so on. If that doesn't help or if the problems keep recurring after the restart, then you should consider the following steps. Apple shows no negative consequences of the reset. Therefore you can use it for trouble shooting.
Instructions for the SMC reset: Reset the system management controller chip
There are different measures to reset the SMC for stationary Apple computers and for various MacBook models. Here I would like to show you the three different approaches. In preparation, the Mac or MacBook must first be shut down (force shutdown if necessary).
There are these differences when resetting:
- Desktop Mac: Turn off the Mac, disconnect the power cord from the power supply for 15 seconds, then wait another 5 seconds and turn the Mac on again
- MacBook with removable battery: MagSafe-Remove the power pack, remove the battery, press the on/off button for 5 seconds, insert the battery, switch on
- MacBook with a fixed battery: Remove the MagSafe or USB-C power supply, Shift + Ctrl + Option (Alt) (everything on the left side of the built-in keyboard) and press the On / Off button for 10 seconds, release, plug in the power supply, switch on
Indication that the SMC may need to be reset
The subheading and the following list are to be understood as quotations. The source is this Apple support page. Here are the cases listed there in which you can consider an SMC reset to solve the problem:
- The computer fans run at high speed even though the computer is not being used heavily and is well ventilated.
- The keyboard backlight is behaving incorrectly.
- The status light behaves incorrectly.
- The battery status indicator, if present, behaves incorrectly (on Mac notebooks without a removable battery).
- The display backlight does not respond properly to changes in ambient lighting.
- The computer does not respond when the power button is pressed.
- The Mac notebook does not behave properly when it is opened or closed.
- The computer goes to sleep or turns off unexpectedly.
- The battery is not charging properly.
- The MagSafe power supply LED does not indicate activity properly.
- The computer is unusually slow even though it is not using an unusually high CPU load.
- Application icons "jump" in the Dock for an excessive amount of time when the associated programs are opened.
- Applications do not work properly or stop responding after opening.
- A computer that supports the screen synchronization mode does not switch to the target screen or back suddenly as expected or suddenly.
- Lights around I / O ports on a Mac Pro (Late 2013) don't turn on when you move the computer.
Were these instructions helpful or missing a detail? Is something unclear or could I help you? Feel free to leave a comment about the reset of NVRAM, PRAM and SMC;)
After graduating from high school, Johannes completed an apprenticeship as a business assistant specializing in foreign languages. But then he decided to research and write, which resulted in his independence. For several years he has been working for Sir Apfelot, among others. His articles include product introductions, news, manuals, video games, consoles, and more. He follows Apple keynotes live via stream.