Comments on: MemTest for Mac OS X Tests your RAM

By: Mats Odman

Mats Odman — Thu, 14 Feb 2013 07:19:41 +0000

After some Internet research I have found out that you have to start up your Mac in Single Mode to get a reliable MemTest. After doing so my iMac 16 GB RAM was reported 100% functional.

With such an amount of RAM be prepared for some waiting… (Almost two hours in my case.)

By the way, by mistake I put 4×4 GB PC3 10600 RAM modules in my Mac and it works, however in the speed of 1333 MHz. That is much better than the previous 1066 MHz.

By: Mats Odman

Mats Odman — Wed, 13 Feb 2013 12:53:14 +0000

What does this mean?

FAILURE! Data mismatch at local BUFA address 0x00000001b7c78f98, BUFB address 0×0000000337466798
BUFA Data: 0×4343434343474343, BUFB Data: 0×4343434343434343

Serious?

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Deals: Save 11% Off Retina MacBook Pro, 28% Off SSD Upgrades, 25% Off 16GB RAM — Sun, 03 Feb 2013 20:57:38 +0000

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By: England

England — Sat, 12 Jan 2013 08:01:12 +0000

VEDY VEDY COOL THX

By: Alex

Alex — Tue, 02 Oct 2012 20:35:39 +0000

Have MBP, installed 16gig, in single user mode 10 time out of 10 no errors. However, when in Multi-user mode – several sub-tests failed few times, could it be that I have a full system up and running? Doing more tests…

MBP 8,2

By: hank

hank — Thu, 20 Sep 2012 22:23:09 +0000

> is it possible that problems exist
> on the parts of memory that isn’t being tested?

Same question. I’ve gotten crashes and panics throughout the year since I bought a mid-2011 Mini; Genius always blames software; software authors say errors are “all over the place” and blame hardware.

Memtest: no problems with 2x2GB (Apple original)
No problems with 2x4GB (OWC RAM)
No problems with one 4GB alone
No problems with the other 4GB alone
Errors with one 4GB and one 8GB
intermittently — about 2 out of 7 passes
Errors with the other 4GB and the one 8GB
intermittently — about the same
No problems with just the single 8GB

Everyone so far says there should be no problem specific to 4+8 = 12 GB.

So either both 4GBs have a problem, or
the one 8GB has the problem

But running them individually doesn’t get the problem.

My best guess is — that using 4+8 lets Memtest test a little more of the 8GB card, and that happens to hit the intermittently failing area.

But this is logic, aka guessing.

Anybody know?

And, is there a bootable CD tester out there I can use that would work on a mid-2011 Mini (using a 3rd party external USB CD drive)?

I tried the Memtest-86 CD, but that doesn’t work on the Mac (esc doesn’t exit, and using esc suddenly reports multiple errors).

By: Gavin

Gavin — Sun, 26 Aug 2012 06:16:12 +0000

I know its been a while since you posted, but I figured I would answer you. My father has the same 2.6 core 2 duo MBP as well. In the system profiler it shows Macbook Pro 4.1 I believe. In any case, OWC reports this model only takes 6gb of ram, not 8. It will address 8 however it will slow down as you are experiencing… so… sorry you’ll have to downgrade to 6, or 4gb.

By: Brad

Brad — Thu, 19 Jul 2012 12:44:26 +0000

I ran it on my mid 2011 iMac which I recently increased from 4GB to 8GB and got the following result.

Requested memory: 6278MB (6583214080 bytes)
Available memory: 6278MB (6583214080 bytes)
NOTE: Memory request is too large, reducing to acceptable value…
Allocated memory: 6102MB

If it only checks 6102MB of the 6278MB it found is it possible that problems exist on the parts of memory that isn’t being tested?

By: Peter

Peter — Mon, 11 Jun 2012 04:47:10 +0000

You should run in single user mode before using on a Mac so it can test more of the memory. Hold command+s when booting your Mac.

By: Jake

Jake — Wed, 23 May 2012 01:58:23 +0000

Update: approaching the 12 hour mark; test sequence 1 is still underway. Anyone out there?

By: Jake

Jake — Tue, 22 May 2012 20:12:04 +0000

Correction, that’s a Core *2* Duo.

By: Jake

Jake — Tue, 22 May 2012 17:19:37 +0000

I just updated my 2009 MBP (2.6GHz Core Duo) to 8GB from 2GB. Apple and Crucial both say the limit is 4GB, but the system recognizes the two 4GB modules just fine in About This Mac and System Profiler.

However, the computer has been VERY slow lately whenever I’m using more than one app at a time. I’m running memtest right now, and it’s been more than three hours so far, still on this first pass. Is this unusual? It’s not crashing or hanging, just going REALLY slow. It just says “15+ minutes” above, so I’m not sure what a reasonable upper bound would be.

Any advice would be much appreciated.

By: Russ

Russ — Thu, 03 May 2012 13:19:24 +0000

The “official” word from Apple is that the MBP line only accepts 8GB. However, according to numerous sources – and confirmed installations – it can actually handle up to 16GB. If it’s any indication, both Crucial and Macsales (OWC) confirm this when you use their system specific memory selectors.

By: Kirtus

Kirtus — Tue, 01 May 2012 15:24:01 +0000

Correct me if I’m wrong, but isn’t the maximum memory capacity of MBP 8 gigs?
Perhaps thats why you fell into the problem

By: Kona

Kona — Wed, 04 Apr 2012 16:52:14 +0000

I bought and installed 16GB upgrade to my MB Pro. The memtest has so far passed 9 out of 10 times. The only one error I received (at the second iteration) was in the Checkerboard, failure at 60, all other times it’s gone through flawlessly. Not sure if I should be concerned.