Problem with 16GB on 2010 iMac 27" i5 & i7.

Yeah, I didn't think that was the problem either.

I formatted and reinstalled too (for other reasons though) and still had the problem. I too have a SSD for my boot drive and a 2TB drive for my secondary. I don't think they were trying to mislead me or anything with the suggestion to rename the HDD (they even said that they doubted it was the issue, but that they wanted to eliminate it as a possible problem).

Like others, I'm having a kernel panic and the machine just shuts off (with nothing written to normal system logs).

One thing I've noticed (as well as others) is that if I take the RAM out or flush the cache (unplug computer, then hold power button for a while) then it takes a few days before the problem happens again. So Apple engineers are looking into the possibility of the problem having to do with memory filling up first or something (I'm not going to pretend to explain what they meant).

Keep pestering them. They are looking into it, but let them know about all these forums posts and how much it's affecting you. Hopefully someone will find a fix soon.

I have the SSD model with an I7. I see others with I5s and have this issue. Does anyone NOT have the SSD?

Are you thinking of a ssd cause, maybe because earlier iMacs which don't have ssd are not having this particular problem?
The power theory makes more sense to me.
A nice test would be for those, who have several kinds of ram available , to put in one slot 2x4 G non problem causing rams(Apple,Samsung Factory) and in the other 2x4 G shutdown problem causing rams (OWC, Crucial etc).

I hope that some readers who can do this will perform this test.


peterwillem

Not necessarily the SSD causing the issue, but possibly a power imbalance. iMac models without SSDs CAN be modified to carry one, but the change is not trivial. In putting patterns together the SSD did cross my mind, as did the processor and video card, but those don't seem to be an issue. But when two others, including myself have SSDs, the question was worth asking.

BTW, whether this thread or another, there was one or two posters with factory-installed Apple RAM having this issue.

Here is the link to that post by Atkinstorefron.
http://discussions.apple.com/thread.jspa?threadID=2588800&start=15&tstart=0

It says somewhere that he uses everything including the ram from the Apple store.

I still like to know if somebody can do my proposed test, written in a post before?


peterwillem

I have test results just back. I'm not experiencing random shutdowns as most of you are, but my machine does shut down when I open a file in Photoshop. 100% reproducible.

I have OWC RAM and Apple RAM and an Apple iMac 11,3, 2.93GHz Core i7 with SSD. I just received an identical new 27" iMac. Here's what I've discovered:

Old iMac + OWC RAM: Crash
Old iMac + Apple RAM: Ok
New iMac + OWC RAM: Ok
New iMac + Apple RAM: OK

Your mileage may vary, as I may have a different problem. But the fact that a new iMac solved the issue with OWC RAM lends more credibility to 3rd party RAM than Apple on this issue, especially given the results from others in using the same RAM on other model machines.

Looks interesting but a little odd to me.
First let me get one thing clear: You have now 2 identical iMacs mid 2010 27" , one being a few months older than the other?

Then you are saying the older iMac crashes only with your OWC ram, the newer one does not crash with either ram.
And all those crashes you can "fire up" by opening some photoshop file.

Is this correctly summarized?

If possible do the following test:

Run both iMacs for a period of time without using photoshop. If in that case you don't experience any shutdowns with both iMacs and using 16 G OWC ram than you have a different problem.
And I would like to know what chipset your OWC ram has, if that is possible (no stickers taped over them as with mine)

I just read in your earlier post that your OWC ram has micron chips. Mine have different chips, cant read which. So the problem lies maybe with the chip the OWC ram is using and apparently
not all the OWC ram are using the same.
So maybe they have found out about the problems and what causes them and changed their chips.

I wait for your results.


peterwillem

Message was edited by: peterwillem

I have two identical Macs. The first one shipped on October 7th from Apple, the second one shipped October 25th from Apple.

Then you are saying the older iMac crashes only with your OWC ram, the newer one does not crash with either ram.
And all those crashes you can "fire up" by opening some photoshop file.
Is this correctly summarized?

Yes

Run both iMacs for a period of time without using photoshop. If in that case you don't experience any shutdowns with both iMacs and using 16 G OWC ram than you have a different problem.

I can tell you now that I did not experience intermittent shutdowns with the old machine and OWC RAM. But I could get it to shutdown when using Photoshop.

And I would like to know what chipset your OWC ram has, if that is possible (no stickers taped over them as with mine)

It was Micron, but I just sent mine back, so I unfortunately can't tell you more. The Apple RAM bling I have now is from Samsung.

Thx,
I bought my OWC ram and iMac around august 6 th. This looks like that in the mean time Apple and/or OWC did something with their iMacs respectively rams.
The chips on my OWC ram show no brand name just numbers and have a sticker on them that says if you remove it, all guaranty is void. I wonder why? Probably it is some cheap/****** one which they changed after the problems arose.
I cannot imagine that Apple did some hardware change to their iMacs in such a short time.
I wonder what chips others have on their OWC ram who are still having these problems?


Quote:
"I can tell you now that I did not experience intermittent shutdowns with the old machine and OWC RAM. But I could get it to shutdown when using Photoshop."


These problems sometimes occurred with long intervals, hours even days. So maybe you did not wait long enough, without using Photoshop, to let them happen.
But we cannot check that now.
Well your shutdown problems are over and mine will remain if using 16 G OWC ram.
But I can live with 12 G for now. It is only that I paid for 16 G without being able to use them fully.


peterwillem

Another update: Renaming the primary boot drive back to "Macintosh HD" did not fix the problem. I would have posted an update on this sooner, but I was away on a business for a bit.

So far the only luck I've been having is to either flush the cache on the machine (shut down the iMac, pull the power cord, then hold the power button for 10 seconds), or reduce the RAM on the machine from 16GB to anything lower (12, 8, or 4).

I'm still in touch with Apple support, but we're not making much headway.

I'm having the same issue. Just throwing in my RAM purchase for another data point. I purchased (4) 4GB SODIMMs for a 16GB upgrade but due to 1 DOA stick, I ran with 8GB for at least a week with no trouble. Here is the RAM:

G.SKILL 4GB 204-Pin DDR3 SO-DIMM DDR3 1333 (PC3 10600) Laptop Memory Model F3-10600CL9S-4GBSQ
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231341

When I put all 4 sticks in, I started getting the random power-off events. Each time I installed the memory, I reset the SMC, PRAM, etc., booted to single-user mode and ran memtestosx until I no longer felt comfortable stressing out my machine. Each time, no problems were found. If heat were an issue, this test would have caused it. Every time I have an event, it seems to just be with normal use (web page browsing, etc.) and not with running VMware, etc. so it doesn't follow memory failure patterns that I have seen in the past.

I'm looking at the list mentioned (Hynix, Micron & Samsung) and wonder if anyone has picked up any more info as to why they work. Is it the chip configuration or something similar causing this?

Again, I may have had a different issue than you, but the OWC RAM I had was Micron. Replacing my system solved the problem, but that is a difficult route to pursue.

Although I could duplicate the issue in the store, the store could not replace the type of machine I had. The online store couldn't find documentation from the store itself, and wanted more tests done. If I didn't return my RAM soon, then I lost the ability to return.

I had one other option because I purchased it through my company's Apple rep. They managed to convince the online store to return it. I had second thoughts about having Apple incur all the trouble, but was relieved when it finally solved my issue.

If I were you, I would go for Samsung memory.

Thanks. After I posted, I went to OWC and purchased 16GB of the Samsung (Apple factory) memory. I'm hoping that this solves my problem. I'm hanging on to my original 2GB Samsung SODIMMs just in case I end up with the 12GB workaround.

Maybe it's due to the fact that the original Apple ram is CL7 while most other 3rd party RAM chips are CL9? I found this on the net:

http://everythingapple.blogspot.com/2009/11/ddr3-1333-mhz-works-in-new-quad-imac s.html

Would like to ask, will these RAMs be ok if install in a quad i7?
http://eshop.macsales.com/item/Other%20World%20Computing/1333DDR3S16S/