Use old iMac as second screen for new iMac
Can I use my iMac mid 2010 21.5 inch as an extra screen for my 2024 iMac 24 inch, M4 chip? If so, how do I connect them?
iMac (M4, 2024)
No — you cannot use a 2010 iMac as a second display for a 2024 M4 iMac.
Unfortunately, Target Display Mode is no longer supported with Apple Silicon Macs (M1, M2, M3, M4).
It also cannot work with a 2010 iMac due to hardware and OS limitations.