Using the iMac as an external display can place additional strain on a MacBook

- GPT

Using your iMac as a display for your MacBook, commonly done through Target Display Mode (or through AirPlay for newer Macs), typically does not harm your MacBook. However, there are a few things to keep in mind to ensure smooth operation and to prevent any issues:

1. Overheating: Depending on the workload you're running, using the iMac as an external display could cause the MacBook to run warmer than usual, especially if both devices are handling intensive tasks like video editing, gaming, or coding. Ensure your MacBook has proper ventilation.
2. Battery and Power Usage: If you're running your MacBook in clamshell mode (closed lid) while using the iMac as a display, it might draw more power, potentially reducing battery life over time. It’s a good idea to use it while plugged in.
3. Software Compatibility: Keep your devices updated to prevent any issues with display lag or crashes. Sometimes, outdated macOS versions can cause problems when using external displays.
4. Performance: Depending on how you’re connecting (e.g., AirPlay vs. cable), you might experience some performance degradation like lag or stuttering if the connection isn’t strong or stable enough.

If you keep an eye on temperature and make sure the system isn't overburdened, using your iMac as a display shouldn’t cause any harm to your MacBook.

 

Using a proper monitor, specifically one designed for external display use, would generally be better for your MacBook in terms of performance and thermal management.