Intel-based Macs: Using Apple Hardware Test

Intel-based Macs: Using Apple Hardware Test

To start up your computer in Apple Hardware Test: Press the power button to turn on your computer. Press and hold the D key before the gray startup screen appears. If Apple Hardware Test does not start up, see the Additional Information section at the end of this article. Note: Some Macintosh computers that shipped with OS X Lion and later support the use of Apple Hardware Test over the Internet. These computers will start up to an Internet-based version of AHT if the hard drive does not contain AHT. An Internet-enabled connection via Ethernet or Wi-Fi is required to use this feature. It takes a minute or so for Apple Hardware Test to start up and inspect your hardware configuration. While this is taking place, an icon appears on the screen: When the process is complete, select your language and click the right arrow. If you aren't using a mouse, you can use the up and down arrows to select a language and then press the Return key. The Apple Hardware Test console appears. You can choose which sort of test or tests to perform: To perform all of the basic tests, click the Test button or press the "T" key or the Return key. To perform a more thorough diagnostic test, select the "Perform extended testing" checkbox under the Test button before you click the Test button.

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MAC解決kernel_task讓cpu突然飆高100%,150%的有效方式
Kernel_task is using over 600% of my CPU and slowing things down to a crawl!!!