NVRAM/PRAM reset can be done only when there is an issue like these:
- Resolution of the screen
- Incorrect battery charge reports
- System booting up with the wrong disk
- Power off your Mac & leave it for few seconds
- Turn Mac on
- Press option key, command key, P and R keys at the same time
- Hold the keys down until your Mac restarts and makes an audible beeping sound
SMC on MacBook, MacBook Air, MacBook Pro
- Shutdown & power off your Mac and unplug the power cable from the machine
- Wait for 15 seconds then plug power cable back in
- Press the left shift key, left option key, and control key all at once and hold down for 10 seconds
- Release the keys and power on your machine as usual
- Power down your Mac and unplug the power cable
- Wait 15 seconds, then plug the power cable back in
- Wait 5 seconds, then turn the power on your Mac as usual
![Wink ;)](./images/smilies/icon_e_wink.gif)