The Pane Startup

The pane Startup is designed to manage special settings of the operating system or of the computer’s firmware, which won’t affect normal operations, but only the startup phase of OS X.


OS X is supporting different startup modes that can be preconfigured with TinkerTool System:

OS X can also start in Safe Mode which means that it will start normally, but only with a minimum set of features enabled. All third-party startup components like drivers, kernel extensions, or background services will remain inactive. This mode is helpful if you installed bad system software or drivers which prevent OS X from starting up correctly. In addition, nearly all system and user caches will be cleared. Safe mode can be activated temporarily by holding down the shift key () during startup. It does not make sense to enable Safe Mode permanently.

Power Control Options

If the option Wake for network access is enabled in the computer’s Energy Saver settings, OS X usually makes use of the function Bonjour Sleep Proxy to automatically wake the computer when another computer accesses a public network service of the sleeping computer. If the network service is not being accessed directly, but a standard Wake On LAN (WOL) signal is sent to the sleeping computer, it might happen with the latest versions of OS X that the computer does not awake completely, but only partially, keeping the monitor off (“dark wake”). This can be sufficient for many remote maintenance features, but it is often desired that the sleeping computer should be powered on completely. In addition, technical problems with certain third-party software products can be avoided.

Startup options
Startup options

By selecting the option Enforce full power-up when receiving wake signal over network (no “dark wake”) you can ensure that the system kernel should perform a conventional, complete wake-up when a WOL signal comes in.

Another power control feature is available via the setting Enforce pre-Lion behavior regarding power control of monitors. New functions, which Apple had introduced with Mac OS X 10.7, and which control the power management of displays, will be deactivated intentionally.

The detail behavior of this setting can be changed by Apple in each version of OS X without notice. Some users had positive results with this setting by keeping the internal display of a mobile computer off, even when the display lid is opened, if an external monitor, keyboard, and mouse are connected. However, we won’t guarantee any specific functionality of this startup option.

Security Options (for OS X Yosemite only)

OS X uses a security feature to ensure that only specific extensions of the system kernel (in most cases this will be device drivers) can become active: The system only accepts a kernel extension if it is digitally signed by its developer and the signature confirms that this developer has official permission from Apple to develop kernel extensions. With this approach, it becomes less likely that an unreliable or even intentionally malicious extension can be installed. This is critical, because a program running as kernel extension has unlimited access to all hardware and software parts of the computer.

However, if you need a certain kernel extension to operate some third-party hardware device, but the vendor has not received permission from Apple yet, it can make sense to (temporarily) deactivate this security check. To do so, set a check mark at Allow system to use unsigned kernel extensions.

Performance Options (OS X El Capitan or later only)

OS X can reconfigure its kernel to optimize itself for working as a server. This means certain system parameters, like the strategy for reserving network and file caches, or the multi-threading characteristics will by modified in a way so that typical server applications gain better performance. Such server applications typically run without a visible user interface in the background and use many threads mainly doing network and file operations. On the other hand, a standard installation of OS X is usually optimized to give the frontmost application running on the graphical user interface the best speed behavior.

If you like to change the default and give typical server jobs better performance, set a check mark at Optimize system for server operations with OS X Server. After restarting the computer, the kernel and some features of OS X Server will respect the new setting.

You can only enable this feature if TinkerTool System detects that OS X Server is used for server operation on this computer. Apple may change the exact meaning of this setting any time without further notice.

Diagnostic Options

Additional options are available for diagnostic purposes:

The generated NMI signal is actually not a true Non-Maskable Interrupt, but an ACPI System Control Interrupt (SCI).

To use one of the listed options, perform the following steps:

  1. Open the tab item Options of the pane Startup.
  2. Activate or deactivate the listed options as desired.


Users can individually set the languages they prefer when working with applications. This personal preference setting is controlled by the priority list displayed at Language & Region > Preferred Languages in System Preferences. However, this setting only affects applications started by each user, it does not apply to the startup phase of the operating system and its login screen, situations where no user has logged in yet. Under normal circumstances, this additional language preference can only be set when installing the operating system.

Startup language
Startup language

TinkerTool System allows you to modify this language preference without having to reinstall the system. Perform the following steps:

  1. Open the tab item Language of the pane Startup.
  2. Select the preferred language with the pop-up button Startup Language.

This will also change the keyboard layout used when running the login screen. If you don’t own the keyboard type typically used for the selected startup language, it may become difficult to enter user name and password correctly.

Under certain circumstances, the startup language setting of OS X can have been damaged, e.g. when you have restored your system from a Time Machine backup. In this case, TinkerTool System will display an additional button with the option to repair the setting.