I have an old iMac 5K, 27-inch Late 2015 3.2 Ghz Quad-Core Intel Core i5, memory 32 GB 1867 MHz DDR3, AMD Radeon R9 M380 2 GB currently runs very slow and Adobe software not running smooth.
Now I using MacBook Pro 16-inch Apple M1 Max with 64 GB memory is that possible use my iMac 5K 27-inch as a 5K monitor for my MacBook Pro?
Is that possible connect thunder bolt 2 from iMac to Type-C from MacBook Pro.
MacBook Pro 16″, macOS 14.3
That setup is no longer supported by Apple. The iMac cannot be used as a monitor for any of the newest Macs and Target Display mode is no longer a feature of macOS, having been deprecated several years ago.
Please see: Use your iMac as a display with target display mode - Apple Support
Per the link above:
• Your target iMac (monitor) must be using macOS High Sierra 10.13.6 or earlier.
• In all cases the source Mac that you're connecting FROM must have been introduced in 2019 or earlier and have macOS 10.15 Catalina or earlier installed.
You might consider a third-party solution - Luna Display or Duet Display - though I can’t speak for the performance of those.
That setup is no longer supported by Apple. The iMac cannot be used as a monitor for any of the newest Macs and Target Display mode is no longer a feature of macOS, having been deprecated several years ago.
Please see: Use your iMac as a display with target display mode - Apple Support
Per the link above:
• Your target iMac (monitor) must be using macOS High Sierra 10.13.6 or earlier.
• In all cases the source Mac that you're connecting FROM must have been introduced in 2019 or earlier and have macOS 10.15 Catalina or earlier installed.
You might consider a third-party solution - Luna Display or Duet Display - though I can’t speak for the performance of those.
That 27" 5K Retina iMac doesn't support Target Display Mode. Target Display Mode went away when the first 27" 5K Retina iMac came out a year earlier, and never returned. No Retina iMacs have it. On top of that, Apple added restrictions such that no current Macs can use any iMac as a Target Display.
My understanding is that Duet Display is a "subscription" (rental) application – and that it doesn't support 5K resolution. That would presumably make it less interesting to the OP.
The OP's iMac is too old to be an AirPlay Receiver for AirPlay to Mac, but I believe that even on recent iMacs, AirPlay wouldn't support taking full advantage of a 27" 5K iMac or 24" 4.5K iMac screen.
So to the best of my knowledge, the Luna Display is the only game in town for using this particular 27" 5K iMac display. As Astropad, and you, point out, that reuse comes with limitations.
Be sure to fully research solutions like Luna or Duet before purchase. The Luna support page has this:
Points 1 and 2 say to me it is not intended to duplicate the performance the primary display.
Also look at their costs compared to that a standard external monitor.
Can iMac 5K, 27-inch Late 2015 as Monitor for MacBook Pro M1?
