Imac 2020 Ram Issue?

[Diamondsr4everyone]

Hi, Okay so I am running into an issue here with my iMac 2020 with a 3.1GHZ 6-core Intel Core i5. So when I got this system used 2 years ago it only came with Micron 8gb 2x4gb sticks of ram. I bought Crucial 16gbx2 for a total of 32gbs of ram and replaced the ram. No issues except a few small unexpected shutdowns when the system was sleeping. Yes I beta test and have macOS Tahoe. So the shut downs never caused me any issues what so ever always turned the system back on and ran like it should with no issues.

Anyways last week I was using safari nothing out of the normal when suddenly out of the blues the iMac just froze. Nothing was moving or working. Just dead froze. Lasted about 30-60 seconds then just bam. Black screen system shut down harder then ever like you held the power button down. Tried to restart to no avail. Though wth. Tried disconnecting the system from the external monitor and all the external hard drivers and nothing.

Thought okay maybe I have a power issue. Checked the power cable getting 122 ac volts. Knew the power wasn't the issue coming to the system. Tried setting it in front of a AC for a little to see if it was overheated. No dice. I tried to reset the SMC which didn't work. I also held the power cable down while disconnection the power and left it sit for 5 minutes again to no avail. Nothing I was trying was working to get the system to power back on. Finally I left it plugged in and walked away to answer a phone call and came back about 1.5 hours later and could hear the system running. Still no screen what so ever.

Finally I shut it down and took the ram out and put one stick in at a time and got the screen to pop in with one stick and not the other. The ram has 4 ports it can go into the bottom is 1 the top is 4 in my case. I have the ram stick in 1 so it works with one ram not the other. I.E. one will turn the system on with the chime and screen the other would give me nothing what so ever. And when I installed them both back into 1 and 3 together I got nothing yet again.

Finally I dug out the ole 8gb ram that was from when I bought it and that wouldn't even turn the system on then again after hitting the power button. So then I tried the other 2 and 4 slots and still got nothing. But when I tried the "known" good ram in only slot 1 it turns on and works just fine. Even if the other 16gb ram is in slot for it only picks up slot 1 and only reads as installed 16gb of ram.

So I did some more working on the ram seeing if the ram was the issue and installed the other "bad" ram in slot one and gave it about 60 seconds and it turned on with a screen so tried the other good ram in slot 3 as well and didn't get it to power on at all. Finally I took the slot 3 ram and installed it in slot 2 so slots 1 and 2 are filled and it took about 60 seconds but chimed and turned on and now its showing I am running 32gbs again.

I am beginning to think this is a memory slot issue or some weird software bug on this system as it's making sense but isn't making sense if you know what I mean. Anyways anyone have any advice for me that would be great because idk what to think. Thanks in advance and sorry for the long trouble shooting story.

 

[wilberforce]

The 2020 iMac is unusual as it likes to have all sticks exactly identical. Apple says this for the 2020 iMac (and only the 2020 iMac):
“For optimal memory performance, DIMMs should be the same capacity, speed, and vendor.”
However we have found if the sticks are not exactly identical, it merely degrades performance (speed) but still works ok.
I think you have a different problem, with a faulty slot or DIMM.

One of the many threads on the topic of memory upgrades to the 2020 iMac:

iMAC 2020 Memory Upgrade

I purchased the 2020 iMAC stock with 8GB of RAM and upgraded to 32GB using Crucial brand memory on the hardware compatibility list. As I went through the process, I found a lot of information - some of it inaccurate. I thought I would share my experience and hopefully save someone else from a...

forums.macrumors.com

Also be aware that the 2020 iMac often takes about 30 seconds to respond after a memory change. People do not wait long enough and give up, thinking the computer is “dead.”

 

[Diamondsr4everyone]

The 2020 iMac is unusual as it likes to have all sticks exactly identical. Apple says this for the 2020 iMac (and only the 2020 iMac):
“For optimal memory performance, DIMMs should be the same capacity, speed, and vendor.”
However we have found if the sticks are not exactly identical, it merely degrades performance (speed) but still works ok.
I think you have a different problem, with a faulty slot or DIMM.

One of the many threads on the topic of memory upgrades to the 2020 iMac:

iMAC 2020 Memory Upgrade

I purchased the 2020 iMAC stock with 8GB of RAM and upgraded to 32GB using Crucial brand memory on the hardware compatibility list. As I went through the process, I found a lot of information - some of it inaccurate. I thought I would share my experience and hopefully save someone else from a...

forums.macrumors.com

Also be aware that the 2020 iMac often takes about 30 seconds to respond after a memory change. People do not wait long enough and give up, thinking the computer is “dead.”

Well it could have been 30 seconds. I was using 60 seconds just because i didnt really time the time.

But yes i like you think this is a different issue thats why i asked and gave all the details. If this is a slot issue only thing i can do is get the slots replaced correct. And i can look into the Dimm and see if that has any issues.

Also thank you for your kind response. It has got me confused and i knew it wasnt dead but it was dead lol.

Also this is Crucial DDR4 3200 C22 ram and yes i do believe the imac is suppose to be 2666mhz. Could it be that simple that the 3200 is the issue. And if so why did it run okay for the past 2 years with it installed

 

[RobertPS]

Your memory is most likely fine.

Safari 26 and MacOS Tahoe (Windowserver) have issues with memory leaks.
This will slow down, freeze and eventually crash your Intel iMac.

I have 64GB Crucial memory in mine and after a week or several weeks uptime Windowserver will freeze or crash the iMac, unless I remember to close and restart Safari and/or reboot once in a while.
This behavior is still present on Mac OS Tahoe 26.5.

After such a crash, the system will either:
- eventually reboot and after login you're fine
- eventually reboot and prompt you as if you just installed the OS. Log in and you're fine.
- freeze and become unresponsive. Manual reboot required.
- show a black screen. Pressing the on/off switch for a (very) long time will eventually cause it to start up again in my case.

Apple must have received dozens of crash reports from my machine alone.
It is always Windowserver crashing.

I have just installed Mac OS Tahoe 26.6 and hope it is fixed.

No such problems on Mac OS Sequoia with corresponding older Safari version (not 26, 26 is slow on Sequoia).

 

[Diamondsr4everyone]

Your memory is most likely fine.

Safari 26 and MacOS Tahoe (Windowserver) have issues with memory leaks.
This will slow down, freeze and eventually crash your Intel iMac.

I have 64GB Crucial memory in mine and after a week or several weeks uptime Windowserver will freeze or crash the iMac, unless I remember to close and restart Safari and/or reboot once in a while.
This behavior is still present on Mac OS Tahoe 26.5.

After such a crash, the system will either:
- eventually reboot and after login you're fine
- eventually reboot and prompt you as if you just installed the OS. Log in and you're fine.
- freeze and become unresponsive. Manual reboot required.
- show a black screen. Pressing the on/off switch for a (very) long time will eventually cause it to start up again in my case.

Apple must have received dozens of crash reports from my machine alone.
It is always Windowserver crashing.

I have just installed Mac OS Tahoe 26.6 and hope it is fixed.

No such problems on Mac OS Sequoia with corresponding older Safari version (not 26, 26 is slow on Sequoia).

Thats also what i have noticed after restarting. I also notice the app memory is high when only safari, mail, messaging, music and settings are open. System keeps going from 18gb app memory to 24 gb app memory used. Closing everything except safari doesnt bring it down either. Close safari it goes away.

I also have reported it quite a few times to apple and notice that the cases are Open with no other reported cases. Makes me think they dont wanna fix it.

On that note how are you running 64gbs on ram when i thought the Intel Imacs were limited at 32Gb???

Now in thay note if this is a memory leak which i am not saying it isnt. But why is slots 3-4 not reading ram. Bad slots???

Thank you also for the answer its helping alot. So i do appericate it alot.

 

[RobertPS]

On that note how are you running 64gbs on ram when i thought the Intel Imacs were limited at 32Gb???

On the 2020 Intel iMac 27" up to 128GB (4x32GB) can be installed. Mine has 2x32GB installed in slot 1 and 3.
I just renewed Applecare (for probably the last year) as it's my main machine.

I suspect bad or dirty (oxidized?) slots in your case. It might help to switch off your iMac, remove the memory, put some IPA on the module contacts and install and remove them a couple of times in slot 3 and 4.

Then let it dry out and see if works. you've got nothing to loose it seems.

 

[Diamondsr4everyone]

On the 2020 Intel iMac 27" up to 128GB (4x32GB) can be installed. Mine has 2x32GB installed in slot 1 and 3.
I just renewed Applecare (for probably the last year) as it's my main machine.

I suspect bad or dirty (oxidized?) slots in your case. It might help to switch off your iMac, remove the memory, put some IPA on the module contacts and install and remove them a couple of times in slot 3 and 4.

Then let it dry out and see if works. you've got nothing to loose it seems.

Thank you so much for all the help.

I can run some ipa in both slots 3-4 and see if that helps both those ports. Hope they arent bad.

This is also my main system and its been a great system minus the random shut downs lol. Which all makes sense now thank to you.

I mean i knew what it was doing i just didnt know why it was doing it. Just hope apple gets off their backsides and actually fixes the issue.

Also your ram im assuming is 3200mhz or does it have to be 2666mhz

 

[RobertPS]

Yes, the RAM is 3200 mHz and it runs on 2667 mHz.
Also, just now checking in system settings it reports the Ram modules are in slot 2 and 4.
Anyway, they are in the same slots as the factory installed 2x4GB was in.

The repeated friction from re-inserting the modules in the slots is important when using the IPA to clean the slots.

 

[Diamondsr4everyone]

Yes, the RAM is 3200 mHz and it runs on 2667 mHz.
Also, just now checking in system settings it reports the Ram modules are in slot 2 and 4.
Anyway, they are in the same slots as the factory installed 2x4GB was in.

The repeated friction from re-inserting the modules in the slots is important when using the IPA to clean the slots.

Got it. I will clean the slots in the next few days. I really really appreciate the help. It means alot. So thank you so much.

 

[benholt]

RobertPS's WindowServer/Safari 26 leak diagnosis is real and worth taking seriously as a separate issue, but it doesn't explain the "one stick works, the other doesn't afterwards" pattern. Those are two different failure modes stacked on each other.

A hard power-kill on an Intel iMac — the kind that happens when WindowServer wedges long enough to trigger the watchdog reset — can stress the memory controller and push a marginal DIMM from working-but-flaky to visibly bad in one event. Before you clean anything with IPA, do a swap test: put the "bad" stick in the slot the "good" stick works in, and vice versa. Bad stick in a known-good slot = bad DIMM, Crucial's Mac-specific SKU warranty is fine to claim on. Good stick in the bad slot = actual slot / trace issue, then the IPA clean is worth trying.

Not the answer you wanted, but on Crucial's 16GB Mac modules I've personally seen a handful of infant-mortality failures after physical trauma or a bad shutdown, so don't rule out a genuinely dead stick just because it was working fine before the freeze.

 

[Diamondsr4everyone]

RobertPS's WindowServer/Safari 26 leak diagnosis is real and worth taking seriously as a separate issue, but it doesn't explain the "one stick works, the other doesn't afterwards" pattern. Those are two different failure modes stacked on each other.

A hard power-kill on an Intel iMac — the kind that happens when WindowServer wedges long enough to trigger the watchdog reset — can stress the memory controller and push a marginal DIMM from working-but-flaky to visibly bad in one event. Before you clean anything with IPA, do a swap test: put the "bad" stick in the slot the "good" stick works in, and vice versa. Bad stick in a known-good slot = bad DIMM, Crucial's Mac-specific SKU warranty is fine to claim on. Good stick in the bad slot = actual slot / trace issue, then the IPA clean is worth trying.

Not the answer you wanted, but on Crucial's 16GB Mac modules I've personally seen a handful of infant-mortality failures after physical trauma or a bad shutdown, so don't rule out a genuinely dead stick just because it was working fine before the freeze.

No I get what you're saying. For the ram I can understand both your points. However I think Roberts on cue with it more. It probably could be an oxidized slot because its been working sense I spoke to him sense and I see both modules of ram. Actually have 18.34gb of memory used as this moment and only have the 2 16gb modules installed. Its been doing much better sense I move the memory to slots 1 and 2 and I noticed with Apples last Safari update its been kinda staying around 20gbs. Sometimes I get to 24 max and then it comes down. Maybe Apple is taking notice I don't know. I still have to do the IPA he mentioned but sense its working I haven't really bothered.

But I thank you all for your help. It's been a wild experience but at least I had the knowledge to get it working again and have help figure out why it did it.