A hardware test used by holding D during boot, to test internal components of a Mac. It was replaced by Apple Diagnostics in Macs released after June 2013.

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1answer
7k views

Testing a MacBook Pro's RAM upgrade

What are the best possible RAM tests that can be run on a MacBook Pro (Early 2011 running Mountain Lion) after upgrading RAM from 4 GB to 16 GB? I see there a quite a few tools out there and the ...
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votes
2answers
9k views

What Information Is Gleaned From Conducting An Apple Hardware Test?

What information is gleaned from conducting an Apple Hardware Test ( or Apple Diagnostics for Macs purchased from June 2013), when trying to find out if something is wrong with my Mac ?
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1answer
237 views

My RAM was bad (“three beeps” bad) until shuffled

I've got an early 2011 13" i7 MBP, OS X 10.10.3 (the public beta version before the one released last night) with 10 GB of RAM – one of the original 2 GB modules in the bottom slot and an 8 GB module ...
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11answers
99k views

Why is Apple hardware test (AHT) not loading when pressing key D on system start?

I purchased a Late-2011 MacBook Pro 15" used a month ago. At the time of purchase, I successfully ran the Apple Hardware Test. I've since installed a new SSD and aftermarket RAM. The computer appears ...
0
votes
2answers
509 views

MacBookPro10,1 goes to gray screen when a USB is inserted

This is a follow up to my other question. Now the problem is sometimes when inserting a USB stick, the computer freezes and goes to a complete gray screen(kernel panic). It seems to only happen if ...
0
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1answer
2k views

Why does my macbook always shut down on recovery?

Hi am trying to fix a MacBook Unibody Model A1342, The macbook has an unknown error that might also be caused by water accident or drop or just internal problems. (I dont know about the macbooks ...
0
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0answers
841 views

What does “-501 0D” mean when trying to run the Apple Hardware Test?

I have a late 2012 iMac running El Capitan which has become quite sluggish. I’ve tried a few software solutions, but I think it’s something wrong with the disk. (A lot of stuff is fine; anything that ...