Mar 16, 2015

How to Reset SMC & PRAM also why we reset them and when we use them??

How To Reset Your Mac’s SMC & PRAM – And Why

Sometimes your Mac will act strange for no apparent reason — lights won’t be working correctly, volume settings will be off, display resolution will change, or a number of other issues that aren’t related to specific apps will pop up. Most of the time, these issues can be solved by closing all of your apps and restarting the computer. Sometimes, though, you’ll need to reset the SMC and PRAM.

What Are SMC and PRAM?

The system management controller (SMC) is a chip in your intel-based Mac that’s involved in running a lot of the physical parts of the machine, like LED indicators, keyboards and other peripherals, cooling fans, and power buttons. It also plays a role in the behavior of your hard drive, how your computer behaves in sleep mode, and the power supply.
mac-pro-smc-board
Parameter random access memory (PRAM) holds information about the configuration of your computer, including things like the date and time, as well as desktop, volume , mouse, and other control settings. It’s powered by a small battery, so these settings don’t get lost every time you turn your computer off.

When Should You Reset the SMC or PRAM?

Most of the time, if you have a problem that requires resetting the SMC or PRAM, your Mac will just be acting strange. It will probably turn on and run the apps you need it to, but some functions will just be wonky. For example, if your SMC isn’t working correctly, you could experience one or more of the following:
  • The battery or status lights behave strangely
  • The keyboard backlight doesn’t work or works incorrectly
  • Your MacBook doesn’t turn on when you open it
  • The power adapter light doesn’t reflect what it’s doing
  • The fan is running at an abnormally high rate, especially under low load
  • The trackpad doesn’t work
  • Your computer won’t connect to Wi-Fi
  • Your computer won’t turn on
  • Target display mode switches on or off unexpectedly
  • Application icons bounce for an extended period of time when opening
  • Your computer runs slowly, even under low CPU load
  • Your computer shuts down slowly
If there’s an issue with your PRAM, you’ll see problems like these:
macbook-pro-boot-error
  • Volume doesn’t respond properly
  • The boot volume isn’t set (you’ll see a question mark before your computer boots up)
  • Strange mouse scrolling and clicking speeds
  • Keyboard not responding normally
  • The time zone or clock changes or won’t change
  • Display resolution changes or won’t change
  • AirPort problems
  • Your computer shuts down slowly
Resetting the SMC and PRAM is the first step toward solving a wide variety of problems, so if your computer just seems a bit off and restarting it doesn’t fix the problem, you should consider resetting one or both of these.

Resetting SMC

Before resetting either the SMC or PRAM, it’s a good idea to close all applications and reboot your computer to see if that fixes the problem. Also, when you restart your computer after resetting either of these, it may take a little while longer to boot up. Apps might take a bit longer to get started too, but they’ll get back to normal speed quickly.
Resetting the SMC is done in different ways depending on the type of computer you have.

MacBook With Removable Battery

  1. Shut down the computer.
  2. Unplug the power adapter.
  3. Remove the battery.
  4. Press and hold the power button for five seconds.
  5. Replace the battery.
  6. Plug in the power adapter.
  7. Turn on the computer.

macbook-battery-cover-removed

MacBook Without A Removable Battery

  1. Shut down the computer.
  2. Plug in the power adapter.
  3. On the built-in keyboard, press the Shift, Control, and Option keys on the left side and the power button, all at the same time.
  4. Release all three keys at the same time.
  5. Turn on the computer.

Mac Pro, Intel-based iMac, Intel-based Mac mini, and Intel-based Xserve

  1. Shut down the computer.
  2. Unplug the power cord.
  3. Wait fifteen seconds.
  4. Plug in the power cord.
  5. Turn on the computer.
When you reset the SMC, you may see the indicator light on the MagSafe power adapter behave a big strangely at first; this is normal.

Resetting PRAM

  1. Shut down the computer.
  2. Press the power button.
  3. Before the grey screen appears, press the Command, Option, P, and R keys at the same time.
  4. Hold the keys until your computer restarts and you hear the startup sound a second time.
  5. Release the keys.
After you reset the PRAM, you might notice that some of your settings have been reset—things like the time, the volume, mouse settings and keyboard preferences, and other things like that. If you remember your previous computer settings, you should be able to get it back to normal in just a couple minutes.

Good to Know

While you shouldn’t have to reset the SMC or PRAM on a regular basis, it’s still good to know what they do and how to go about fixing issues that you may come across. If your computer’s behaving strangely and restarting the machine doesn’t help, you know what to do! You might also want to try one of these eight resources for troubleshooting your Mac.
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