32GB in mid 2011 27" iMac too much for Mavericks to deal with....

Question

Level 1

77 points

32GB in mid 2011 27" iMac too much for Mavericks to deal with....

I recently came into good fortune and 'won' 4 x 8GB of Komputerbay Mac Memory, DDR3 1333MHz PC3-10600 204 pin Non EEC 9-9-9-24 new memory.

Well actually fell lucky when Amazon listed the full 32GB for £53 so I bought it and they delivered.

The irony is if I put all 32GB in the iMac - the iMac gets really unreliable, Finder, Calendar, App Store Mail, Contacts etc etc just keep crashing every 10 seconds.

If I put in 24 GB everything is fine

If I put in 26GB 3x8GB and 1x2GB everything is fine.

If I put in 1x8GB everything is fine.

If I put in each of the 4 x8GB in one at a time everything is fine and stable.

I can put in any combination of 3x8GB sticks and everything is fine - even rotating them between slots.

But if I put all 32 - 4 x 8 GB then silly season starts.

Anyone got any ideas/clues?

It is an i7 3.4GHz 27" mid 2011 iMac.

Everything looks good until it is not ....

More than happy with 26GB btw - enough to run and create a good size RamDisk for video scratch disk

Ta

iMac, OS X Mavericks (10.9), iMacs, iPads, iPhones, TC, AEs, ATV

Posted on Dec 30, 2013 11:49 AM

Reply

Answer 1

rkaufmann87

Level 10

140,418 points

Dec 30, 2013 11:57 AM in response to Busta999

iMacs are extremely sensitive to RAM, the specifications have to virtually identical to what Apple recommends and even then there are some brands that simply do not work.

It is also possible that one of the DIMMs is defective. You need to test each DIMM individually and if you continue to have problems I would recommend returning the RAM and buying from a reliable vendor such as OWC (www.macsales.com) or Crucial. My guess is you are located in Europe somewhere so I'd recommend Crucial.

32GB works just fine in a late 2011 iMac assuming the following conditions are met:

RAM is fully seated
No defective DIMMs installed
Correct specifications

Reply

Answer 2

Busta999 Author

Level 1

77 points

Dec 30, 2013 12:04 PM in response to rkaufmann87

Thanks

I have tried each DIMM individually without issue and in combinations of threes, equally without issue.

These are DIMMS expressly labled for iMac mid 2011 27 inch and all the specs are to Apple's definition with the exception of course that the maximum is 16GB :-)

Realistically if I can run at 26GB reliably for £53 then I am doing exceptionally well

Thaks anyway - just thought it curious

Regards

Reply

Answer 3

rkaufmann87

Level 10

140,418 points

Dec 30, 2013 12:08 PM in response to Busta999

OK, I run 24GB in my late 2011 27" iMac, for my needs it's plenty and works very well. If your machine getting Kernel Panics then you may want to post the KP report and see if there is something else going on that is software related. If you don't know how to log a KP report please look over http://support.apple.com/kb/ht2546

Reply

Answer 4

Busta999 Author

Level 1

77 points

Dec 30, 2013 1:06 PM in response to rkaufmann87

Well the good news they are not kernal panics, as defined in the kb at the link you sent.

Just every app crashing :-)

I'll see how it runs on 26GB and hopefully it will remain stable and sell the remaining 8GB for the orignal £53 :-)

Reply

Answer 5

baltwo

Level 9

62,362 points

Dec 30, 2013 1:55 PM in response to Busta999

As Roger noted, you need to test each module. Run the Apple Hardware Test suite, extended tests at least twice, followed by Rember.

Reply

Answer 6

Busta999 Author

Level 1

77 points

Dec 31, 2013 1:11 AM in response to baltwo

Thanks but it doesn't work

Followed instructions to letter three times

Each time goes straight, after a long wait to login screen

No AHT not AHT logo

Just a very flakey machine and no hardware tests

Btw disconnected everything then put USB keyboard on it and power

Press power

Immediately press and hold D, still holding D down when login screen appears

Time to reset NVRAM?

Reply

Answer 7

baltwo

Level 9

62,362 points

Dec 31, 2013 1:19 PM in response to Busta999

Yes, you can try these. Reset the NVRAM/PRAM and Reset the SMC

Also, you should be able to run the AHT via Internet recovery mode. Might need the EFI firmware update. See http://support.apple.com/kb/HT4904 and http://support.apple.com/kb/ht1509

Reply

Answer 8

SeaPapp

Level 7

26,486 points

Dec 31, 2013 2:33 PM in response to Busta999

Crucial sells 1.35v memory for your iMac

While the Komputerbay ram is 1.5v

I wonder if that's the problem? FWIW OWC also specs theirs at 1.5v

Reply

Answer 9

Busta999 Author

Level 1

77 points

Dec 31, 2013 4:39 PM in response to SeaPapp

Thanks all, did some research found out how to install the hardware tests.

Put all 4 Dimms and ran tests - died

Spent day putting one Dimm at a time and running tests, all passed the simple tests

Been runnin extended hw tests all day, each Dimm takes 1hr 4 mins

Except one that went on for over 2 hours before I had to run up the mac for a family movie, will continue tomorrow.

I wonder if the voltage is an issue, would certainly explain why 3 Dimms work, and 4 don't

Reply

Answer 10

rkaufmann87

Level 10

140,418 points

Dec 31, 2013 4:57 PM in response to Busta999

With everthing I've read I'm positive you bought incompatible RAM. You can stay with the 24GB or return and buy the proper RAM. Continuing to test and crashing your system could damage the OS so I would recommend stopping while you are ahead. If you decide to return and repurchase this time buy from a proven vendor such as OWC (www.macsales.com) or Crucial. Sometimes a bargain isn't always a bargain.

Reply

Answer 11

Busta999 Author

Level 1

77 points

Jan 1, 2014 3:27 PM in response to SeaPapp

You may well be correct but the 1.35v is for DDR3L standard, not straight DDR3 which is 1.5v

It may well be the issue, but if it is, it is a problem with implementation not necessarily with the memory as Apple specify DDR3 not DDR3L.

It runs stable at 26GB, more than enough for the foreeable future. If the need arises, or I have stability problems I will for out another £254.35

Komputerbay are a US company from Georgia, and they have hundreds of great reviews, they are alright.

I am WELL over the stated 16GB RAM so will consider myself a winner, after all how often do you get 32GB of this memory for £53 or $87 US, from a reputable company like Amazon, another American company.

Thanks for all your assistance and help

Reply

Answer 12

Busta999 Author

Level 1

77 points

Jan 1, 2014 3:28 PM in response to rkaufmann87

I think Amazon is a proven vendor, I doubt many would challenge their presence in the marketplace.

Reply

Answer 13

rkaufmann87

Level 10

140,418 points

Jan 1, 2014 3:31 PM in response to Busta999

Busta999 wrote:

I think Amazon is a proven vendor, I doubt many would challenge their presence in the marketplace.

Sure I buy from Amazon all the time but come on, you know as well as me they don't specialize in computer stuff. They're great for buying stuff online and they provide good guarantees but guarantees that their stuff will work in your computer.....LOL no way! When it comes to RAM then buy from a proven RAM vendor.

Reply