iMac won't boot after ram upgrade

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Level 3

674 points

iMac won't boot after ram upgrade

For some reason, my iMac late 2013 3.4Ghz quad core i5 won't boot with new ram modules added. New ram is exact same specs as original that came with the iMac. I've tested the new ones on their own in the iMac, and the system boots up fine. Same goes with just using the original ram. But when I put all 4 together, the iMac doesn't boot up. Not even the chime.

Combinations I've tried are:

1-Old

2-New

3-Old

4-New

No boot

1-New

2-Old

3-New

4-Old

No boot

1-New

2-Old

3-New

4-empty

No boot

1-Old

2-New

3-Old

4-empty

No boot

1-New

2-Old

3-Old

4-New

No boot

1-Old

2-New

3-New

4-Old

No boot

The only combinations that work are:

1-New

2-empty

3-New

4-empty

Boot good

1-Old

2-empty

3-Old

4-empty

Boot good

I just got off the phone with Apple, and they are saying all modules have to be the same size. ie. all 4GB or all 8GB. Can't mix and match sizes. Which is strange, because I've never heard of this. My Mac Pro has different speed ram modules, with different sizes in it. As long as I install ram in pairs, it runs like a charm. I've even heard the new iMacs don't have to have ram installed in pairs.

I'm wondering if slot 2 and 4 are maybe damaged? I haven't tried using just slot 2 and 4. To my understanding, you have to use 1 and 3 first. Can anyone confirm this?

Also, I've read a couple of people had to wait 30 seconds for the chime when they installed new ram in their iMacs. I didn't wait 30 sec to see if it would boot. Never heard of any Mac taking 30 sec to just chime in. lol Has anyone else experienced this? Is there a fix? Tx.

Mac Pro, Mac OS X (10.6.8), 4x1TB,10GB Ram,Radeon HD2600 256MB

Posted on Jan 9, 2014 9:41 AM

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Answer 1

Aug 5, 2017 8:32 AM in response to mattwithcats

I guess I'm reviving an old thread but I am having a similar problem.

I am trying to up grade my mid 2010 27# iMac from 4Gb of RAM to 8Gb. I have four 2GB memory modules that are identical in every way except for the serial numbers. New and old memory work as pairs or mix matched in DIMM0 banks but when add memory to DIMM1 banks the iMac does nothing on power up. I even let sit for over 5 minutes, still nothing.

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Answer 2

babowa

Level 9

78,103 points

Jan 9, 2014 9:45 AM in response to Eric Shawn2

Well, I don't have a brand new iMac, so I can't say if what Apple said is correct except that I have seen threads here with people mixing different size RAM successfully; however, my first question would be:

What brand RAM and is it the exact same specs as stated by Apple?

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Answer 3

Kappy

Level 10

361,741 points

Jan 9, 2014 9:46 AM in response to Eric Shawn2

RAM must be installed in matched pairs. Same size in the two upper slots and the same size in the lower slots. However, the size in the upper two slots and lower two slots need not be the same. All modules need to have the same specs, and those must match the requirements for your model.

You must also be sure the modules are seated fully. It can take considerable pressure to get them to "click" into place fully.

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Answer 4

babowa

Level 9

78,103 points

Jan 9, 2014 9:49 AM in response to Kappy

The latest iMacs no longer have two slots side by side; they have 4 slots arranged vertically; slot 1 + 3 must be matched, and slots 2 + 4.

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Answer 5

Jan 9, 2014 9:53 AM in response to Eric Shawn2

CLICKY CLICK---> iMac: How to remove or install memory

Or

Apple>About This Mac>More Info>Memory: Double click "Memory Install Instructions" at the bottom right of window.

my iMac late 2013 3.4Ghz quad core i5

Conflicting info. Your system profile shows: Mac Pro, Mac OS X (10.6.8). Please update/correct.

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Answer 6

Kappy

Level 10

361,741 points

Jan 9, 2014 10:07 AM in response to babowa

Thank you, babowa. 🙂

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Answer 7

Eric Shawn2 Author

Level 3

674 points

Jan 9, 2014 10:35 AM in response to babowa

Thanks Babowa and Kappy. Which is the set up I have. Modules are matched pairs.

1+3 has 4GB modules and 2+4 has 8GB modules. I've even tried switching that order to 1+3 8GB modules and 2+4 4GB modules. Still no luck. Both are confirmed to have the same specs. New ram is Mushkin 204-pin DDR3L PC312800 1600Mhz SODIMM. Same specs as the original modules that came with the iMac. Except they are 8GB modules instead of 4GB. I use Mushkins in my Mac Pro, and they work just fine.

As I mentioned, each set used by themselves, the iMac boots with no issues. It's only when all 4 are used at the same time, that the iMac doesn't start. Not even a chime, or warning chimes. I've spoken to a couple of IT guys at work about the 30 sec comments I've read. They said, sometimes, systems takes a little longer to start up when new ram is added. Apparently because it does a diagnostics before it actual starts to boot. I didn't try waiting that long after hitting the power button. I'll give that a go when I get home from work. Will post back with results.

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Answer 8

Eric Shawn2 Author

Level 3

674 points

Jan 9, 2014 10:28 AM in response to Baby-Boomer-USofA

No error. I still have my Mac Pro. The iMac is a new purchase. Giving to my sister. I'm setting it up for her.

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Answer 9

Jan 9, 2014 10:45 AM in response to Eric Shawn2

So noted.

Did you read the info in the link I posted and/or through About This Mac?

Installing RAM in the newer iMacs that are RAM user removable are a PITA. You must have the strength of Hercules to push the RAM securely into the slot. To confirm that the RAM is seated properly you should hear a loud snap! Did you hear a snap?

I tried w/mine & was unsuccessful for 2 days of trying. Apple paid for a tech to come to my home to install the RAM which was 3rd party! The tech was from the store I purchased my iMac from. I was still with-in my 14 days to return warranty.

I can tell you that tech is was in his early 30's had one knee on my couch (iMac was face down on couch), I was holding the iMac steady while the tech tried for 5 minutes for each RAM to snap in w/o breaking.

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Answer 10

Eric Shawn2 Author

Level 3

674 points

Jan 9, 2014 10:57 AM in response to Baby-Boomer-USofA

Hey Boomer, I went through all info yesterday. Including the install instructions in About this Mac, just to make sure I wasn't missing anything. When I installed all modules, they all snapped into place. You can hear and feel them snap in. I made sure they were all securely placed. Memory install 101. ;-) Just like making sure power cord is connected first when your computer doesn't start up. lol

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Answer 11

Jan 9, 2014 10:56 AM in response to Eric Shawn2

😁

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Answer 12

babowa

Level 9

78,103 points

Jan 9, 2014 12:54 PM in response to Eric Shawn2

I'm going to go out on a limb here because I've seen a couple of posts here and there - some people seem to be experiencing a similar problem as the late 2009/mid 2010 iMacs did (I have one of those) - there was no problem if all 4 slots had OEM RAM and there was no problem if there was a mix of OEM and third party, but much less than the stated max capacity either. However, there were problems when it was close to or max capacity of a mix or only third party RAM.

Here is the link to one of the very lengthy discussions from 2010:

https://discussions.apple.com/thread/2588800

Since you said that it works with either installed, I'm wondering if it's either a brand or a size mixture issue.

I don't have any experience with Mushkin; I always get mine from OWC (Crucial is the other much recommended brand here); iMacs appear to be the 'finickiest' of Macs both with RAM and Superdrives.

@ Kappy:

you're welcome 🙂

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Answer 13

Eric Shawn2 Author

Level 3

674 points

Jan 9, 2014 2:00 PM in response to babowa

Thanks for the link babowa. Reading through several of them, the people with issues say their iMacs act strangely, including random shutdowns. Which means even with their issues, their iMacs still boot up. Mine doesn't at all with all 4 modules installed. I'd also like to think that Apple would have corrected any of these issues from 2009/2010 models on the newer late 2013 models. I thought maybe the timing was off between the two sets. But both sets are CL11. So timing shouldn't be an issue either.

I'm going to try the 30 sec wait and see what happens. If that doesn't work, I'm going to get another set of the Mushkins, so that all modules are exactly the same brand, size and specs.

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Answer 14

babowa

Level 9

78,103 points

Jan 9, 2014 3:14 PM in response to Eric Shawn2

I said I was going way out on a limb (but I did see some threads here) ....... Hope getting four of the same works for you - personally, I would have ordered new ones from OWC or Crucial and returned the Mushkins..... but that is my opinion.

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Answer 15

Jan 9, 2014 3:34 PM in response to babowa

Not to step on anyones toes here but I was always told to buy Top of the Line Ram. And there are different thoughts about Matched Pairs.

It has been my expieriance to Use either Crucial or Other Word Computer;s Ram in Matched Pairs to avoid Problems. Period.

This way you avoid fooling around for a couple a days trying to figure out why your machine won't boot up.

And after wasting your time you go get top of the line Ram and your problem goes away like magic.

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