Key combinations to troubleshoot your Intel-based Mac at start-up

Many articles you read about Mac troubleshooting mention troubleshooting methods such as resetting the NVRAM, starting in FireWire Target Disk Mode, starting in Safe Mode, or starting in Single-User Mode, but fail to explain exactly how to do that. This article breaks it down for you.

Apple has released a knowledge base article describing the key commands and what they enable when pressed during start-up:

• Press C during start-up: Start from a bootable CD/DVD, such as the Mac OS X Install disc.
• Press D during start-up: Start the Apple Hardware Test when the Install DVD 1 is inserted in your Mac's drive.
• Press and hold (Command + Option + P + R) until you hear two beeps: Reset the NVRAM.
• Press Option during start-up: Loads Startup Manager, enabling users to select which volume they would like to boot from. Pressing N will show the first bootable Network volume as well.
• Press the Eject button, press F12, or click and hold the mouse or trackpad button: Ejects any removable media.
• Press N during start-up: Attempt to start from a compatible network server (NetBoot).
• Press T during start-up: When two Macs are connected via FireWire, this will start one in FireWire Target Disk Mode (two Macs with FireWire ports are required).
• Press Shift during start-up: Starts your Mac in Safe Mode, temporarily disabling log-in items.
• Press (Command + V) during start-up: Starts in Verbose Mode.
• Press (Command + S) during start-up: Starts in Single-User Mode.
• Press (Option + N) during start-up: Start from NetBoot server using the default boot image.

Apple recommends pressing the start-up key combinations immediately after hearing the start-up tone.

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