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New 2020 5k iMac having trouble with 4 new dimm sticks. 3 new +1 OEM work just fine. :o

M

manhattanmac

macrumors newbie
Original poster
Aug 17, 2020
2
0
Howdy,

I bought a 64gb ram upgrade kit from OWC for my brand new 2020 5k iMac, 27 incher. However, strange boot issues abound when I try to install all 4 sticks at once.

2 OEM sticks and 2 empty slots = boot normally
1 OEM stick + 3 OWC sticks = boot normally
4 OWC sticks = failed boot

When the boot fails, I get only a black screen. The display doesn't power on at all, but I can hear the fan try to spin up every 30 seconds or so, but only spins for maybe 1 second and then spins down again. This process repeats until I pull the power cable. I've also tried just about every configuration to see if I have a faulty OWC stick, or a faulty RAM slot. Every OWC stick works by itself. Every RAM slot works by itself. It's just that weirdly, installing all 4 OWC sticks causes a failed boot even though no single stick is bad.

Does anyone have any thoughts as to what is causing this or a potential solution?

Thanks!
 
manhattanmac said:
Howdy,

I bought a 64gb ram upgrade kit from OWC for my brand new 2020 5k iMac, 27 incher. However, strange boot issues abound when I try to install all 4 sticks at once.

2 OEM sticks and 2 empty slots = boot normally
1 OEM stick + 3 OWC sticks = boot normally
4 OWC sticks = failed boot

When the boot fails, I get only a black screen. The display doesn't power on at all, but I can hear the fan try to spin up every 30 seconds or so, but only spins for maybe 1 second and then spins down again. This process repeats until I pull the power cable. I've also tried just about every configuration to see if I have a faulty OWC stick, or a faulty RAM slot. Every OWC stick works by itself. Every RAM slot works by itself. It's just that weirdly, installing all 4 OWC sticks causes a failed boot even though no single stick is bad.

Does anyone have any thoughts as to what is causing this or a potential solution?

Thanks!
Click to expand...
Did you call OWC and work with tech support on it yet? They have a really good support team. Let us know what you find out.
 
I have had the exact same problem. Booted the iMac with OEM RAM, fine. Replaced with 4x32GB and it wouldn't pass the memory test. It just spun the fan every 30 seconds for 1 second and repeat. Drove me nuts. I thought I had nailed it down to a bad DIMM slot in the iMac, but then I tried the OEM sticks in slots 1 (bad) and slot 3 and the iMac booted.

But then it got weirder. Running on the OEM RAM in slot 1 and 3, I couldn't install a requested Catalina Supplemental Update. It would download, reboot to install, but then fail and reboot again only to post the message that my iMac crashed and then continue booting. Again I would be told there was a supplemental update for Catalina waiting for me.

I switched back to OWC RAM in slots 2 & 4 (good slots) and would get the same problem during the Catalina update's reboot.

Apple Tech support seemed to agree it might be a hardware problem and suggested SMC reset (which happens when you replace RAM) and re-install the OS. We booted to Recovery partition, ran First Aid on both volumes (HD & HD Data) and then re-installed Catalina which included the supplemental update I was told.

After running benchmarks and other heat stress loads, I decided to try all four OWC DIMMs again and ... for reasons I don't understand, the system booted fine. I've since done many, many reboots trying to get the prior condition to recur, but it seems stable in this configuration. Maybe I switched the DIMMs around in the slots and randomly found a combination that the iMac liked.

I still want to talk to OWC support and see if this could be something else before my return window expires. I hope this story helps others who are going crazy.
 
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I have a question that is not super related but wanted to see if i could get a quick answer. I have 2X32 Sticks coming for my new iMac (2020). I’ve replaced RAM many times on machines I’m currently using but never a brand new one. Do I need to boot the machine first before install the new RAM? Or can I just install the new RAM and then boot the machine for the first time.
 
manhattanmac said:
Howdy,

I bought a 64gb ram upgrade kit from OWC for my brand new 2020 5k iMac, 27 incher. However, strange boot issues abound when I try to install all 4 sticks at once.

2 OEM sticks and 2 empty slots = boot normally
1 OEM stick + 3 OWC sticks = boot normally
4 OWC sticks = failed boot

When the boot fails, I get only a black screen. The display doesn't power on at all, but I can hear the fan try to spin up every 30 seconds or so, but only spins for maybe 1 second and then spins down again. This process repeats until I pull the power cable. I've also tried just about every configuration to see if I have a faulty OWC stick, or a faulty RAM slot. Every OWC stick works by itself. Every RAM slot works by itself. It's just that weirdly, installing all 4 OWC sticks causes a failed boot even though no single stick is bad.

Does anyone have any thoughts as to what is causing this or a potential solution?

Thanks!
Click to expand...

did You call them? Ordered same memory configuration from owc. Waiting for memory and mac to arrive. This is concerning.
 
Donnation said:
I have a question that is not super related but wanted to see if i could get a quick answer. I have 2X32 Sticks coming for my new iMac (2020). I’ve replaced RAM many times on machines I’m currently using but never a brand new one. Do I need to boot the machine first before install the new RAM? Or can I just install the new RAM and then boot the machine for the first time.
Click to expand...

I am sure you can just install the extra RAM and boot first time. But, I would always run the iMac for a day or so with the out of the box configuration just to nail any obvious Apple hardware issues. Given the issues people are having when adding not fully compatible RAM, I would want to be doubly sure that the Apple configuration was stable before adding RAM.
 
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gilby101 said:
I am sure you can just install the extra RAM and boot first time. But, I would always run the iMac for a day or so with the out of the box configuration just to nail any obvious Apple hardware issues. Given the issues people are having when adding not fully compatible RAM, I would want to be doubly sure that the Apple configuration was stable before adding RAM.
Click to expand...

Thank you!
 
CheesePuff said:
FYI I opened my 2020 iMac out of the box and immediately removed the Apple RAM and put in my third party RAM (4x 8 GB chips) and booted it for the first time that way, no issues.
Click to expand...

Oh that’s really good to know, and that’s what I’d prefer to do. Thank you!
 
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CheesePuff said:
FYI I opened my 2020 iMac out of the box and immediately removed the Apple RAM and put in my third party RAM (4x 8 GB chips) and booted it for the first time that way, no issues.
Click to expand...

Is 4 x 8 better then 2 x 16. If so, why?
 
CheesePuff said:
I had a slightly better deal for the 4x 8 GB chips so that is the only reason that I went that route, and that I probably won't be upgrading to 64 GB anytime soon.

If you do 2x 16 GB chips make sure to put them in the 1 and 3 slots for dual-channel efficiency.
Click to expand...
I almost want to upgrade to 64GB just so I’ll never have to worry about being short of RAM.
 
OWC Support mentioned this hint:
the Newer imac models do require, when only two modules are installed, to be installed into specific slots. Often the two slots the Apple RAM came installed into.
Click to expand...
Which could explain why my new DIMMs did not work in slots 1,3 as a pair, but worked in slots 2,4 as a pair since those were the same slots the OEM modules arrived in.

This doesn't explain all my problems, but does explain some of them.
 
FYI, OWC support is great. I'm glad they have a lifetime warranty on these DIMMs because... my 2020 iMac is dead/dying and won't boot or stay up, even running the original DIMMs from Apple. So the iMac going back to Apple today and I have to order another one.
 
mechapreneur said:
OWC Support mentioned this hint:

Which could explain why my new DIMMs did not work in slots 1,3 as a pair, but worked in slots 2,4 as a pair since those were the same slots the OEM modules arrived in.

This doesn't explain all my problems, but does explain some of them.
Click to expand...
That’s weird I have my 2x32gb in slots 1 & 3 as those were where I had higher benchmark scores and are working perfect ...
 
Just to tie this off: I got my replacement iMac last week and had zero problems upgrading all four DIMMs with the same OWC modules I tried the first time. I started with 2x32 in slots 1 and 3, replacing the OEM DIMMs. Booted up with 64GB just fine. Then I added two more to the open slots and now have 128GB. My first order was clearly having logic board issues.

I will mention that I thought my performance was off since Geekbench 5 multicore was consistently low (<8,200) running at 8GB RAM, but sped up nicely when I upgraded to 64GB (10,001). A clear and repeatable 25% improvement. The memory upgrade is definitely a good return on investment.
 
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mechapreneur said:
Just to tie this off: I got my replacement iMac last week and had zero problems upgrading all four DIMMs with the same OWC modules I tried the first time. I started with 2x32 in slots 1 and 3, replacing the OEM DIMMs. Booted up with 64GB just fine. Then I added two more to the open slots and now have 128GB. My first order was clearly having logic board issues.

I will mention that I thought my performance was off since Geekbench 5 multicore was consistently low (QUOTE]

Did you see any improvement going from 64 to 128?

I have 64 but thinking on getting another 64 to be covered on future compatibility issues.
Click to expand...
 
I saw no significant or repeatable improvement going from 64GB to 128GB. I bought the extra DIMMs solely for future proofing and to ensure all four slots worked before my return/warranty windows expire.
 
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Thanks, also considering that but still not sure whether really need the 128.

Very rarely I get mem pressure about 70% with 64GB
 
Been a while, but I was able to fix the issue by calling OWC and having them send replacement ram. For some reason, the replacement ram worked fine. Still not sure why.
 
I am having same issue, I have "iMac (Retina 5K, 27-inch, 2019) or 19.1", with the 8GB (2x4). Ordered 2x8GB from OWC and regardless how I add (1/3 or 2/4) OWC memory it was not working. Called support and one of the steps was to clean memory (gold pins) with the alcohol. That did not help out, so they are sending me replacement memory that should be here tomorrow. I will update once I get it.
 
Update:
Got my replacement RAM, and again did not work so I decided to test every single stick individually to make sure. From both shipments (2x8) only one OWC stick did work, they are most likely from same batch as there is only 120 units difference in serial numbers.

Somewhat disappointed as in my mind OWC was always reliable and then I get one stick from two orders that did not work. However, their tech support was good as always......

I did call technical support to let them know one stick from each order was not working and to see what should I do as I was not able to get all 4 sticks to work together. I thought same sticks (size/brand) should be in 1/3 or 2/4, but they told me no, its ok to have same in 1/2 and 3/4 and it would not impact performance.....also that is only combination which did work for me.

Hope this helps with troubleshooting who ever is in the same situation...

If Apple was somewhat cheaper I would have went with them, but they just overpriced for additional memory

Combination Worked - Total 16GB
S1: OWC 8Gb
S2: Empty
S3:OWC 8 Gb
S4: Empty

Combination did NOT Work
S1: OWC 8Gb
S2: Apple 4Gb
S3:OWC 8 Gb
S4: Apple 4Gb

Combination did NOT Work
S1: Apple 4Gb
S2: OWC 8 Gb
S3:Apple 4Gb
S4: OWC 8 Gb

Combination Worked - Total 24GB
S1: OWC 8 Gb
S2: OWC 8 Gb
S3: Apple 4Gb
S4: Apple 4Gb


Combination I did not try
S1: Apple 4Gb
S2: Apple 4Gb
S3: OWC 8 Gb
S4: OWC 8 Gb
 
I installed two 32gb ram sticks from owc into my new imac in slots 3 and 4. Moved apple ram stick from slot 3 to slot 1. How long will the black screen last when I startup?
 
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