[HOWTO] Use Apple Hardware Test and other diagnostics to test for hardware

[Giaguara]

If you suspect your Mac might have a hardware failure, you can use the bundled Apple Hardware Test that came with your Mac.
These tests are model specific, so using the discs of your PowerBook on your Mac Pro will not work.

If you get odd graphical errors, shutdowns, applications crash with or without a pattern, or there is some other behavior that makes you suspect the hardware, testing it is very easy.

On an Intel based Mac, insert Mac OS X Install disc 1 that came with your Mac to your Mac, and hold letter D at boot. This will load it to the hardware test.
After language selection, use ctrl-L keyboard combination to get it to loop mode, and select extended test, and let it run at least for a few hours. You can end the test with the same keyboard combo, or it will stop if it finds an error.

For testing graphical or RAM errors, it is best to run the test at least for the evening, or even better to let it run the test overnight. If you will receive an error message on the screen, this will indicate where the error lies. (In doubt, post the error here and someone will find out for you).

For PPC based Macs, use the Install Disc 1 that came with your Mac, hold down alt or option key depending on your keyboard, select the Hardware Test from the menu, and the menu selections and loop mode are as for Intel based Macs.

If you don't have those install discs available, and suspect faulty RAM you could run Memtest. Memtest is an option also when you have the discs if you need to test your RAM. There is a Windows version out there, and a Mac version http://www.memtestosx.org.

[dq101]

Cool I didn't know that I just use the Apple PPC test cd or whatever it's called.

[DeltaMac]

Recent Intel models don't need a disk at all. Just reboot holding the D key.

[Diver_Dan]

Hi,

I just registered as I've been receiving kernel panic errors on my Mac Pro (quad core version 1,1). I ran the Apple Hardware Test and got this error message:

4MEM/40/40000001 : B:1 C:[a string of symbols and letters] R:0

I assume this is a RAM error, but I don't know how to determine which stick is faulty. My current RAM configuration is a pair of 512MB sticks in DIMM 1 & 2 on Riser A, and a pair of 1024MB sticks in DIMM 3 & 4 on Riser A.

Can someone help me with this diagnostic?

Thanks,
Diver_Dan

[Satcomer]

Yep. You will something more capable to test RAM. You need something like Rember(with a link to MemTest).

[DeltaMac]

Or, try swapping the two 512 chips on the same riser. Run the test again. If the failure is the same, try swapping the 1GB chips, then run the test again.
Also, a memory error will sometimes show up in your System Profiler, under the memory tab, or the Diagnostics tab might also show a memory error, listing the (sometimes cryptic) memory location.
You can also try swapping one pair into the other riser, then run the test again.
Or, removing one pair completely, then check the test again, then remove that pair, and test again with just the other pair installed.
Be prepared to accept that reseating the memory may fix the error. It might not ever recur, or could be just a temporary fix. The memtest utility can be helpful, too.

[Texas Mac Man]

If you don't have a Apple Hardware Test CD, you can download the software for some model Macs at the site below. Then you can burn a CD.

Apple Hardware Test Images and Information
http://www.info.apple.com/support/aht.html

Cheers, Tom