iMac 2020 crashing

@TaraLeeOm - Just giving you a heads-up that I resolved the problem (and many others). Turns out there is a genuine problem with OWC RAM and the new 2020 iMacs. Removed all the OWC RAM and used 128GB of Apple OEM Micron RAM (from Crucial) and all the problems I've been having for three months disappeared literally minutes after the install. I great, unexpected bonus is that my new iMac runs about 45 degrees cooler, and the fans rarely go above idle. I mentioned my progress on another thread, and many other users have experienced the exact same problem with OWC RAM and resolved it the same way.

Here's the thread...

https://discussions.apple.com/thread/251962728?answerId=254170742022

I had the exact same problem. I purchased a new 2020 iMac last month. 10-core i9. The Apple reseller I purchased it from upgraded it to 128GB of OWC RAM before being delivered to me. It was tested (by them) prior to shipping to me.

After a week of easy usage, I started hitting the machine hard with video encoding, really getting the temperature up high. It began crashing, especially when encoding in Final Cut Pro and using Safari at the same time. I could duplicate the crash each and every time and it would crash several times per day. After numerous calls to Apple support, and a trip to the Genius Bar after everything failed, the kept the machine for a few days and could not duplicate the problem. All their diagnostics said the components were fine.

Running out of options, the only thing I could question was the OWC RAM used by the reseller. I decided to remove the 128GB RAM and install the original 8GB RAM that came with the machine to begin my own testing.

The machine behaved normally immediately after I used the original 8GB RAM. The new RAM was the problem. I then used different combinations to determine which RAM card was bad. They all behaved fine in pairs, but not the entire 128GB together.

I then dipped cotton q-tips in alcohol and wiped the RAM connectors on the card. Three of the cards were clean, one card had a yellow residue that wiped off, in addition to being rough on the Q-Tip. One card had a residue that OWC's own website stated can sometimes occur.

I reinserted all 128GB RAM cards, and my machine has been working fine for the one week I've had it. I suspect that reside on that one card was causing major problems.

Give that a try and see if it works for you.

I understand that. It's only for testing. If you have the original RAM that was in your iMac, re-insert it. If your machine does not crash under the same load, that at least will start you on the path. All our problems were related to OWC RAM. You're the first to discuss similar issues with Kingston. I don't know if Kingston is made at the same factory under a different name.

Also - Crucial RAM is actually made by Micron, which also is the same brand that Apple uses for their OEM RAM. So while you may not find Crucial memory in your country, check for Micron.

I’m running Memtest86 on my iMac. Stock 8GB Apple RAM generated no errors.

My OWC 128GB RAM modules kicked pages of errors, until freezing, crashing, then rebooted.

I’m now in the process of rotating RAM sticks until I narrow down which RAM card is the culprit. Going to be a long night.

What System version are you running?

Download and apply the macOS Catalina 10.15.7 Combo Update   

It has the following GPU fix which might (or might not) help:

• Addresses a graphic issue that may occur on iMac (Retina 5K, 27-inch, 2020) with Radeon Pro 5700 XT

It wouldn't hurt to run it even if you don't have the 5700 XT.

Imacs are extremely sensitive to RAM. Please answer these two questions:

• Did you buy Either Crucial.com or MacSales.com RAM
• Did you buy them from either Crucial.com or Macsales.com directly or did you use a reseller?

Most experienced users on these forums will only purchase Crucial.com or Macsales.com RAM, why simple, it works, the prices are very competitive, the vendors provide great support and the RAM has a lifetime warranty.

Download and run Etrecheck. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Add Text button to include the report in your reply. How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report

IMPORTANT:

Before running Etrecheck assign Full Disk Access to Etrecheck in the Etrecheck's Privacy preference pane so that it can get additional information from the Console and log files for the report:

Also click and read the About info to further permit full disk access.

Then we can examine the report and see if we can determine what might be causing the problem.

I saw one poster remove all of their RAM and then clean the contacts with Isopropyl Alchohol which seemed to work, apparently there was some residue on the contacts that made for bad contacts resulting in the crashes. Somthing worth a try.

Well, so far so good. The repair shop installed a new logic board.

I installed several software apps and all seems well. I've been on it for several hours yesterday and several hours today and there have been no crashes.

I'll check back here in a few days; if all is still well by then, I'll feel safe to say that it's fixed.

Sorry, got a new iPad and it defaulted to some strange user.

Anyway again, my iMac has been perfect since they replaced the logic board. And mine also was crashing more and more before I brought it in for repair.

Another user reported recently that they had 128 GB of OWC RAM in a 2020 iMac and was crashing every day multiple times. They removed the OWC RAM and ran with just the Apple RAM with no crashes.

The replaced the OWC RAM with Crucial.com RAM and haven't had a problem since.

You should try running without the OWC RAM and see if you get crashes.

I heard back from the repair shop. Seems there’s an issue with the logic board and they are ordering me a new one.

Just to chime in, I’m experiencing same issue. Complete freezing up of system, have to manually restart with button on back of iMac. I too am running OWC ram. And I’ve also noticed this is occurring when the fans are spinning. For me, Adobe CS, photoshop, illustrator and/or bridge is spiking CPU usage causing heat/fans and ultimately crashes. Way too often! Apple was telling me it’s software, but maybe it is the ram. I’m gonna try swapping for a few days to see.

Although windows running on boot camp cranks call of duty with insane frame rates for hours on end without crashing. So software may be the issue. Mac OS that is.

I'm confused... I re-read the entire thread to make sure, but are you also experiencing the same issue? I see a "Jared576" as the OP, but didn't catch that you had that same issue. That's a bummer.

Mine had that same problem... freezes when pushed hard, fans go full speed for a second, then machine shuts down. Since I cleaned the RAM contacts, and re-seated RAM, it all seems okay now. I'm going to push it some more in the next few days and will contribute where I can. That's frustrating for sure.

In order to test if it's the OWC RAM or not, you must remove it to eliminate it.