Often we need to access specific features on our computers when things go wrong or if we start tinkering around with our hardware configurations. Sometimes you just want to see how things are running or maybe your just curious. Either way, here is a list of different key combinations that you can use to access special features built into your Intel Mac.
All of these key combinations should be pressed as soon as you hear the startup sound when turning on your Mac. You will want to keep these keys pressed until your Mac performs the requested function.
(Having issues with your startup disk, screen resolution, audio issues? Resetting the NVRAM may help resolve these issues. )
Press Option-Command-P-R until you hear startup sound a second time.
Want to start your Mac with bootable media, USB thumb drive or DVD?
Press “C” during startup.
Eject Removable Media
Press Eject, F12, or hold the mouse or trackpad button.
Safe Boot (similar to Windows Safe Mode)
Hold “Shift” during startup.
Verbose Mode (Let’s you see what’s happening during boot-up instead of the Apple Logo)
Press Command-V during startup.
Single User Mode ( As the name suggests, it’s boots into a single user and without a GUI)
Press Command-S during startup.
OS X Recovery System
Press Command-R during startup.
Startup Manager ( A GUI that allows you to choose which volume to boot with)
Press “Option” during startup.
Apple Hardware Test ( As the name suggests, it tests your hardware and reports issues)
Press “D” during startup.
Target Disk Mode (Turn a Firewire connected Mac into a external Hard drive)
Press “T” during startup.
NetBoot (Allows you to boot from a Network “Default Boot Image”)
Press Option-N during startup.
NetBoot (Allows you to boot from a Network “Use Compatible”)
Press “N” during startup.