I am noticing some issues with my updated Microsoft Office suite, where I am encountering increasing sudden shut downs of the application. I have an iMAC 27 inch display 2020, and I have upgraded the RAM to 128 MB. So, I wondered whether I might purchase a Mac mini and use my iMac as a monitor alone. I look forward to your feedback.
Michael G
In simple terms, no.
Review the document: Use your iMac as a display with target display mode - Apple Support
Target display mode is a feature available with late 2009-Mid 2014 iMacs. The display Mac has to be running macOS High Sierra or older and the signal producing Mac has to be running macOS Catalina (ca. 2019) or earlier.
I’d remove the added memory, and see if the iMac stabilizes.
iMac can be very sensitive to issues with memory, and third-party memory not supported for use in iMac can be problematic. And even in-spec memory such as that from OWC can have hardware issues.
As for your question about re-use of an iMac with Retina display, as correct stated in the earlier reply, no.
To add to MrHoffman's suggestion if you didn't get your additional memory modules from OWC (MacSales.com) then they are more likely the cause of your problems.
Mac's are extremely sensitive to memory module quality. OWC is the only supplier that tests its models in the Mac model they are intended for.
As MrHomman suggested remove the non-Apple memory and see if the problem persists.
That iMac is not designed to be used as a hardware monitor for any other device. Apple got rid of Target Display Mode when the first 27" 5K iMac came out in Late 2014, and never brought the feature back.
They also added restrictions such that no current Mac supports using any iMac (even an older iMac) as a Target Display.
Using the iMAC as a monitor rather than as an all in one computer
