XDA Basics: Can I use an external monitor with the M1 iMac?
Apple’s new iMac is here, complete with pretty colors and an M1 processor. We called the MacBook Air with M1 the best affordable laptop for Apple users, and the iMac should deliver that level of quality for desktop users. But before you order, you’ll need to know if you can still use your sweet multi-monitor setup. The answer is that it depends on how many monitors you want to use.
The 24-inch iMac with M1 supports one external monitor with up to 6K resolution and a 60Hz refresh rate (which coincidentally is a specification that perfectly matches with the Apple Pro Display XDR). That does not mean that you can use multiple lower-resolution screens. If you attempt to use more than one external screen, it will just start mirroring the display. You also won’t find success by trying to connect displays to separate ports.
This is a limitation of all M1-powered Macs. Apple’s own documentation says that you can’t increase the number of supported monitors by using a dock either. The only exception is the Mac mini, which lets you connect one display on the USB 4 port and one on the HDMI port. The 24-inch iMac does not have an HDMI port.
It’s worth noting that while the MacBook Air is one of the best laptops with Thunderbolt 3, it’s actually not delivering on one of the Thunderbolt promises. Thunderbolt 3 should support dual 4K monitors on one port.
For comparison, the Intel-powered 27-inch iMac has a wide array of external display options. You can connect dual 4K displays or one 6K display on one Thunderbolt port. If you’ve got a model with an AMD Radeon Pro 5700 or Radeon Pro 5700 XT, you can connect dual 6K displays.
The short answer is that as long as you’re looking for a dual monitor setup, you’re good to go with the 24-inch M1 iMac. Of course, one of those two displays is going to be the iMac itself. If you need three or more screens, you’ll have to go with another solution. For example, DisplayLink’s Graphics Connectivity driver promises a solution to the problem. You’ll need an adapter as well, and we’ll test this out once we have a unit.
If you’re looking to go for a higher refresh rate but lower resolution monitor, we’re still exploring which combinations are possible — apparently, Apple does not have a clear answer either.