iMac won't boot after adding ram

gslrider

macrumors 6502
Original poster
Nov 4, 2005
321
7
I got a late 2013 iMac i5 3.4Ghz quad core. It came standard with 2 x 4GB PC3 DDR3L 12800-1600. I bought 2x Mushkin 8GB PC3 DDR3L 12800-1600. When I install the new ram set, my iMac doesn't boot. No startup chime, no sound, no screen. Like it wasn't getting any power. I've confirmed that power isn't the issue.

I removed the ram upgrades, and the iMac booted without issue (with the original ram set). So at first I thought the new ram modules I bought were bad. But because I didn't hear the 3 chimes, I decided to test them out. So I pulled the original ram modules that came with the iMac, and replaced them with the upgrades. And low and behold, the iMac starts up without issue. So now I've confirmed that all ram modules are not defective, and are of the same specs. The only difference is 2 are 8GB, and the other 2 are 4GB. This model maxes out at 32GB.

Can anyone explain, or point me in the right direction to find out why this is happening, and what I can do to fix? I don't understand why each set will work alone, but not together. Thanks.
 

gslrider

macrumors 6502
Original poster
Nov 4, 2005
321
7
The new set of RAM modules might be DOA. Try using one at a time only. That way you'll be able to weed out the bad one.
As I mentioned, no bad ram. All ram modules work. Just not all four together. Or 3. The only combination I haven't tried, is using one 4GB and one 8GB.
 

Bear

macrumors G3
Jul 23, 2002
8,089
4
Sol III - Terra
As I mentioned, no bad ram. All ram modules work. Just not all four together. Or 3. The only combination I haven't tried, is using one 4GB and one 8GB.
You may have a pair of bad ram slots... put the original ram back in and take it in to Apple since it's still under warranty.
 

DeltaMac

macrumors G3
Jul 30, 2003
9,910
2,531
Delaware
Re-check the original RAM. Is it really labeled as DDR3L, and not DDR3?
Could be that you can't mix DDR3 and DDR3L in the same computer.
 

gslrider

macrumors 6502
Original poster
Nov 4, 2005
321
7
Re-check the original RAM. Is it really labeled as DDR3L, and not DDR3?
Could be that you can't mix DDR3 and DDR3L in the same computer.
I confirmed that as well. Says DDR3L right on the modules of the original ram. From what I've read as well using DDR3 or DDR3L should make a difference.

First time iMac owner. Always had Mac Pros. Never had any issues upgrading ram on the Mac Pros. Just as long as ram was installed in pairs. I've even used different speed ram in one of my Mac Pros. They were faster ram than the recommended speed. No issues. The system just drops the speed of the ram to the max on the board.
 

IA64

macrumors 6502
Nov 8, 2013
413
0
Can you put the serial number of the new RAMs ?

Also did you try to change the combination of the RAMs installed ? like :

1- Old
2- New
3- Old
4- New

Also, Can you try to put 1 old and 1 new together only and see if it boots ?

Note that When I installed my new RAMs ( Kingston 32GB ) I had to wait 30 seconds for the Chime.

iMac comes with DDR3L and mine installed were LoVo ( low voltage 1.35V RAM ) so voltage is not an issue.

Let's see the latency of these.
 

gslrider

macrumors 6502
Original poster
Nov 4, 2005
321
7
Hey IA64. I've tried that combination, doesn't work. Other combinations I've tried are:

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

1-New
2-Old
3-New
4-Old
No boot

The only combination that works 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 you confirm?

Also, 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 Do you have to wait 30 sec for the chime each time now? Or was it just that one time?
 
Last edited:

DeltaMac

macrumors G3
Jul 30, 2003
9,910
2,531
Delaware
The only combination that works 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.
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 you confirm?

Also, 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 Do you have to wait 30 sec for the chime each time now? Or was it just that one time?
I think that whoever you talked to at Apple either told you incorrectly, or you misunderstood what was said.
http://support.apple.com/kb/HT5908
There is no such requirement to use all RAM at the same size (you do that for "best performance"), other than each slot can take 4GB or 8GB - or empty. Test it yourself, with one chip in one slot. Put the same one chip (assuming it works) in each slot, one test at a time.
I suspect that the timing is off between the two brands of chips, and I also would point the "finger of blame" at the Mushkin chips (IMHO) - so works alone, but not with the RAM that SHOULD work. Just what I would do: Send the Mushkin RAM back, and replace with another brand, such as Crucial, or OWC, or DMS - http://www.datamemorysystems.com/ap...z-27-me089ll/a-cto-late-2013-memory-upgrades/
 

IA64

macrumors 6502
Nov 8, 2013
413
0
Hey IA64. I've tried that combination, doesn't work. Other combinations I've tried are:


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 you confirm?

Also, 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 Do you have to wait 30 sec for the chime each time now? Or was it just that one time?
I had to wait only the first time. My iMac came with slot 1 and 2 filled only. 3 and 4 were empty.

Also there are different product number for your RAMs. Without the correct Model number of your RAMs I can't tell if you should face an issue or not.

Can you post it ? It's found on the RAM box.
 

gslrider

macrumors 6502
Original poster
Nov 4, 2005
321
7
Thanks Delta. According to the specs, the Mushkins should be timed correctly to Apple iMac standard ram (CL11). I use Mushkins in my Mac Pro and they work just fine. Hence why I went with them again. The Mushkins do work on their own. Just now with the original ram. And vice versa.

IA64, if it helps, here's a link from the local distributor I picked up the modules from. http://www.canadacomputers.com/product_info.php?cPath=24_309&item_id=055519 According to the specs latency is 11, just like the original ram. I'm going to wait longer to see what happens. I think the longest I waited for something to happen was a few seconds (max 15 sec), before I disconnected the power cord. If that doesn't work, I'll have to see if another brand will. Will post back.
 

IA64

macrumors 6502
Nov 8, 2013
413
0
Thanks Delta. According to the specs, the Mushkins should be timed correctly to Apple iMac standard ram (CL11). I use Mushkins in my Mac Pro and they work just fine. Hence why I went with them again. The Mushkins do work on their own. Just now with the original ram. And vice versa.

IA64, if it helps, here's a link from the local distributor I picked up the modules from. http://www.canadacomputers.com/product_info.php?cPath=24_309&item_id=055519 According to the specs latency is 11, just like the original ram. I'm going to wait longer to see what happens. I think the longest I waited for something to happen was a few seconds (max 15 sec), before I disconnected the power cord. If that doesn't work, I'll have to see if another brand will. Will post back.
The specs of your new RAM are identical to the stock one. Same latency, bus speed and voltage.

You should not have an issue.

When you boot with stock RAM check the Bank/Module number :

Example in this screenshot :





As far as I know, Stock RAM should be in the same Bank ( 0 or 1 ). Your new ones should be in the other Bank - Dual Channel configuration --
 

gslrider

macrumors 6502
Original poster
Nov 4, 2005
321
7
The specs of your new RAM are identical to the stock one. Same latency, bus speed and voltage.

You should not have an issue.

When you boot with stock RAM check the Bank/Module number :

Example in this screenshot :

Image



As far as I know, Stock RAM should be in the same Bank ( 0 or 1 ). Your new ones should be in the other Bank - Dual Channel configuration --
Hence the perplexing manner of this issue. lol Because I can't actually see all four on screen, I checked the memory info in About this Mac for each set (one set installed at a time). Except for the size, both sets come up as the same specs (DDR3 1600Mhz SODIMM). And I installed all 4 modules as they should be installed. One set in 1+3 slots, the other set in 2+4 slots.
 

IA64

macrumors 6502
Nov 8, 2013
413
0
Hence the perplexing manner of this issue. lol Because I can't actually see all four on screen, I checked the memory info in About this Mac for each set (one set installed at a time). Except for the size, both sets come up as the same specs (DDR3 1600Mhz SODIMM). And I installed all 4 modules as they should be installed. One set in 1+3 slots, the other set in 2+4 slots.
If I were you, I'd buy another 2 new modules and sell the Apple ones.
 

SaSaSushi

macrumors 601
Aug 8, 2007
4,098
492
Takamatsu, Japan
I confirmed that as well. Says DDR3L right on the modules of the original ram. From what I've read as well using DDR3 or DDR3L should make a difference.
Your read correctly and here is another good example of the multitude of factors that can be involved with RAM compatibility issues.

It sounds like the Mushkin just doesn't like the Apple RAM. I concur with IA64 and recommend you either get rid of the Apple RAM and go all Mushkin or return the Mushkin and try a different brand.
 

drambuie

macrumors 6502a
Feb 16, 2010
751
0
As far as I know, Stock RAM should be in the same Bank ( 0 or 1 ). Your new ones should be in the other Bank - Dual Channel configuration --

Actually, it's the other way. If you have two different sized pairs, one matched pair should be in DIMM0, and the other pair in DIMM1. If you think of BANK as Channel it makes sense. The list in system info is not the actual physical order of the slots. To verify the proper order look at the memory layout diagram in About this Mac. If you have 2 x 4GB and 2 x 8GB each row in the diagram should contain a matched pair. This is for dual channel performance for the entire 24GB. If the DIMMs are paired as 4+8 and 4+8, you will still get dual channel performance for the first 16GB. Only the memory between 16GB and 24GB will be single channel. This is because the Intel memory controller will use dual channel for the lowest value in the pair, so 4+8 will be dual channel for 4+4.
 

IA64

macrumors 6502
Nov 8, 2013
413
0
Actually, it's the other way. If you have two different sized pairs, one matched pair should be in DIMM0, and the other pair in DIMM1. If you think of BANK as Channel it makes sense. The list in system info is not the actual physical order of the slots. To verify the proper order look at the memory layout diagram in About this Mac. If you have 2 x 4GB and 2 x 8GB each row in the diagram should contain a matched pair. This is for dual channel performance for the entire 24GB. If the DIMMs are paired as 4+8 and 4+8, you will still get dual channel performance for the first 16GB. Only the memory between 16GB and 24GB will be single channel. This is because the Intel memory controller will use dual channel for the lowest value in the pair, so 4+8 will be dual channel for 4+4.
indeed, I was confused between Bank ( whatever that means ) and channel.

I Think they should have Wrote DIMM/Bank instead of Bank/DIMM but thanks for the correction.
 

gslrider

macrumors 6502
Original poster
Nov 4, 2005
321
7
Success! Installed the original 2 modules back with the new ones. Hit the power button and waited about 30 sec. Booooong! lol Now it starts up instantly. Thanks for that tip IA64.
 

drambuie

macrumors 6502a
Feb 16, 2010
751
0
indeed, I was confused between Bank ( whatever that means ) and channel.

I Think they should have Wrote DIMM/Bank instead of Bank/DIMM but thanks for the correction.
I agree that Apple's terminology is a bit odd here. For triple channel it would be very obvious as there would be BANK 0, 1, and 2, with DIMM 0 and 1 for each. I assume that's the way it would be in the Mac Pro with triple channel RAM. Asus motherboards use letters for the channels, and numbers for the DIMMs, so for dual channel you'd have A1, A2, and B1, B2 in that order on the board. If you only had two DIMMs you would fill A1 and B1.
 

drambuie

macrumors 6502a
Feb 16, 2010
751
0
To gslrider, I added a pair of 8GB Kingston SODIMMs to my late 2012 iMac for 24GB total. They were KVR16S11/8 I got from Canada Computers. They have been rock solid. The OEM Apple 4GB DIMMs and the Kingston 8GB DIMMs I bought use the same Hynix series chips, so compatibility is assured.
 

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