2 questions from new 2020 27" iMac owner

[vett93]

I bought this 2020 27" iMac to replace my aging MacPro 6,1. As a data scientist and photography enthusiast, I think the Intel CPU would give me more mileage for the next few years. I have two questions regarding my new iMac and would appreciate some help.

1. How do I use this iMac as an external monitor for MBP? The Target Display mode is not supported by 2020 iMac anymore. Is there a way that I can use iMac as a 2nd display for my MBP?

2. My iMac has interop issues with external monitors. When I do photography, I'd like to use two external monitors, one 4K and one HD, as additional displays. But there are times when I just want to use iMac's display. However, when I power off these two external monitors, the HD monitor still shows up under System Preferences' Displays. The 4K monitor works as expected. In other words, the problem is only with the HD monitor. Both monitors are connected to iMac via HDMI cable and the white TB3-to-HDMI adapter from Apple. I have swaped cables and adapters. But the probelm with the HD monitor is still there. For these two external monitors, I have an external surge protector with individual switches that can turn on/off each outlet individually. I also have swapped the HD monitor with another HD monitor. It does not solve the problem either. All these three monitors (4K, HD and HD) are Dell UltraSharp monitors.

I don't want my iMac thinks that a HD monitor is still active when it has been powered off already. So how do I fix this problem? I have contacted Apple support and chatted with a Sr. Advisor. But he did not know what to do either.

This new iMac has pretty good benchmark numbers from Geenbench 5.

It is a decent upgrade from my MacPro 6,1.

The iMac's fan is quite loud under load though....

 

[SWolfe]

I use this dub-c dongle from Astro lab to connect my iMac 2020 to my iMac 2012 so I can use the 2012 as an external monitor. It can work over wireless or you can use a lan cable. It can also let you use iPads and other devices as a 2nd monitor like sidecar but supports way more devices. They are also doing windows support shortly as a free upgrade.

https://shop.astropad.com/products/luna-display

 

[SWolfe]

As far as I know you can use this dongle to connect almost any Mac that has either a usb-c or a mini display port so you are no longer a slave to Target Display model since apple pulled support on new devices (that was a nasty surprise when I got my 2020). Since it worked so well on my 2019 and 2012 iMac I just assumed when I bought the 2020 it would be supported.

 

[vett93]

I want to use iMac 2020's display as an external monitor for a MBP. Will this work?

 

[SWolfe]

this is off their website so yes it should work.

• Mac-to-Mac: Use an extra Mac as a second display — works on older Macs too!
• Luna Display turns any Mac or iPad into a wireless second display for Mac.

 

[SWolfe]

But I would still email the company and confirm.