IMAC 2011 27" 20gb ram - kernel panic

dany74m

macrumors member
Original poster
Aug 5, 2012
84
0
Los Angeles - California
Hi,

I read that unofficialy the IMAC support 32 GB di ram. So I ordered to crucial 2X8GB kit, and added to my IMAC to have in total 20GB. Everything looked fine, until I started to work heavily with Adobe Premier. In fact during the edit my Imac started to have randomic Kernel Panic attacks!

So i tried To remove the 4 GB and everything looks fine, I mean no panic attack anymore.

What do you think the problem is?
1) Imac is not stable with more then 16gb di ram
2) the brand of the ram are different, so they are not really compatible.

Any experience about this?

I would love to have more Ram, so if the problem is the brand compatibility, I will order more from crucial hoping that now it will be compatible.

Thank you.
 

thekev

macrumors 604
Aug 5, 2010
6,721
1,820
Sometimes mixing ram can cause problems, so yeah it might be the combination. Did you test the ram when you received it? This should always be the first thing you do. Run memtest or something like that for 5 cycles. Let it run overnight. If any errors come up, send the ram back. Sometimes you just get bad ram, although certain companies have better quality control than others.
 

dany74m

macrumors member
Original poster
Aug 5, 2012
84
0
Los Angeles - California
Sometimes mixing ram can cause problems, so yeah it might be the combination. Did you test the ram when you received it? This should always be the first thing you do. Run memtest or something like that for 5 cycles. Let it run overnight. If any errors come up, send the ram back. Sometimes you just get bad ram, although certain companies have better quality control than others.
Actually I did not test the ram, and since now that I removed the 4gb I don't have any kernel panic, I excluded that the ram is faulty. But anyway I will test, is a good thing to do. So do you exclude that the problem is because the ram was 20gb, more then the nominal max of 16gb?
 

M0esmac

macrumors 6502a
Apr 25, 2012
750
28
UK
Actually I did not test the ram, and since now that I removed the 4gb I don't have any kernel panic, I excluded that the ram is faulty. But anyway I will test, is a good thing to do. So do you exclude that the problem is because the ram was 20gb, more then the nominal max of 16gb?
Problem is that you mixed RAM's. Apple's sock RAM's arent bad.

Get another 8x2 from Cruical and that will be fine.
 

thekev

macrumors 604
Aug 5, 2010
6,721
1,820
Actually I did not test the ram, and since now that I removed the 4gb I don't have any kernel panic, I excluded that the ram is faulty. But anyway I will test, is a good thing to do. So do you exclude that the problem is because the ram was 20gb, more then the nominal max of 16gb?
Someone already said it, but mixed ram can sometimes create issues. They have been tested with 32. It's still a good idea to test your ram when you install it. You're better off this way. If something is wrong, you catch it early.
 

Lancer

macrumors 68020
Jul 22, 2002
2,123
82
Australia
Thanks for the heads up, I was looking at getting more RAM for my iMac (when I get it) but don't want to get some and then have to dump the Apple RAM. I also don't want to spend extra buying Apple RAM.
 

joe-h2o

macrumors 6502a
Jun 24, 2012
997
443
What on earth is it that you guys do that requires so much freaking RAM? 20GBs really?
Sometimes you just need a lot.

I know I'll be putting at least 16 into my new machine so that I can run a VM alongside OS X without having to strangle either OS.

For most people though, vast quantities of RAM will have diminishing returns, but 2x8 GB is cheap, so why not flesh out your machine and give it some breathing room?
 

dany74m

macrumors member
Original poster
Aug 5, 2012
84
0
Los Angeles - California
What on earth is it that you guys do that requires so much freaking RAM? 20GBs really?
Im a professional Videographer and I need to edit 1080p full HD footage. 16gb is really the minimum to do that and FCX will easily use all the ram. Since extra 16gb are really cheap and keeping opened other apps will spead up my workflow, I added 16gb more for a total of 32.
 

JordieG8

macrumors newbie
Jun 22, 2009
7
0
I'm running this RAM along with the 4 Gigs my iMac came with for a grand total of 20 Gigs and I'm having no issues. I ran a Memory tester and a hardware test.

It definitely sounds like you have some bad RAM somewhere. I would pull the new RAM and run a test, if it passes you probably have a compatibility issues or and issue with the new RAM.
 

dany74m

macrumors member
Original poster
Aug 5, 2012
84
0
Los Angeles - California
I'm running this RAM along with the 4 Gigs my iMac came with for a grand total of 20 Gigs and I'm having no issues. I ran a Memory tester and a hardware test.

It definitely sounds like you have some bad RAM somewhere. I would pull the new RAM and run a test, if it passes you probably have a compatibility issues or and issue with the new RAM.
Thank you. I removed the 4 gb original, and I added 16gb more of the same kind from crucial. I run some mem test and everything was fine. Since now no more panic attack.
 

ndraves

macrumors member
Jan 19, 2011
96
1
UK
Good to know the 32GB works well in the iMac. Didn't think it would be a problem but nice to know for sure

What on earth is it that you guys do that requires so much freaking RAM? 20GBs really?
I run a few VMs and they eat RAM, literally! I'm still getting regular page outs on my 32GB when I run too many high RAM VMs. Will be getting the 16GB RDIMMS next for the MP
 

JordieG8

macrumors newbie
Jun 22, 2009
7
0
Thank you. I removed the 4 gb original, and I added 16gb more of the same kind from crucial. I run some mem test and everything was fine. Since now no more panic attack.
Its sounds like it was a compatibility issue. I'm glad you got it sorted out.