Capture card vs Encore.
For an old iMac as a monitor.
A cheap HDMI capture card turns the iMac into a window onto any HDMI source: a Mac, a console, a Blu-ray player. It costs about $20 and works from any device with HDMI out. For a second monitor for a Mac, you need an iMac on macOS 14 for the app we found, the picture depends on the card, and the iMac's keyboard and mouse are not involved. Pick a capture card if you want the iMac to show something other than a Mac. Pick Encore if it is a Mac you want to extend.
Who should pick which
- Pick a capture card to show a game console, camera or any HDMI device on the iMac, or if you want a route that needs no app on the source device.
- Pick Encore to extend a Mac on macOS 14 or later, to use any iMac from Late 2009, and to use the iMac's keyboard and mouse over a cable.
Side by side
| Encore | HDMI capture card | |
|---|---|---|
| Cost | Free during the public beta | About $20 for the card, plus an HDMI cable |
| What the sending device needs | A Mac on macOS 14 or later | Any HDMI output |
| What the iMac needs | macOS 10.13 or later; Legacy for older | macOS 14 Sonoma for the HDMI Monitor app in 9to5Mac's guide, so a 2019 iMac; other viewers are possible, untested by us |
| Connection | Wi-Fi, Gigabit Ethernet or Thunderbolt | HDMI into a USB capture card |
| Picture | Sharp, lossless picture over a cable; Retina iMacs at up to 2560 x 1440 | Limited by the card; check its specification. Many affordable cards send compressed 1080p video over USB |
| iMac keyboard and mouse (camera and microphone coming soon) | Yes, over a cable | No |
| Smart display when idle | StandBy clocks, weather, calendar, AirPlay music, Hey Mac | No |
How it works
An HDMI capture card presents the HDMI signal to the iMac as a USB video source. Your Mac sees the card as an ordinary HDMI display and extends onto it. On the iMac you run an app that shows that video full screen. 9to5Mac's guide uses a roughly $20 card and the free HDMI Monitor app, which needs macOS 14 Sonoma, so a 2019 or newer iMac without unofficial patches.
Limits
Resolution and refresh depend on the card, and many affordable cards send 1080p video. A 27-inch iMac has more pixels than that, so a 1080p card shows a scaled picture on a 2560 x 1440 or 5K panel. 9to5Mac's guide doesn't cover latency. And it needs an HDMI port on your Mac, or a USB-C to HDMI adapter on a MacBook Air.
When the hardware route wins
If you want to show a PlayStation, a camera, or a work PC on your iMac, the capture card route needs no software on the source. Encore only works from a Mac. For more on using the iMac's parts, see driver boards for a permanent hardware conversion, and the cable guide if you want the software route.
Facts on this page were checked on 9 November 2026 on the linked pages. Speeds are each maker's own figures, not independent measurements. Something out of date? Tell us and we fix it.
Questions
Can I use HDMI to connect my MacBook to an iMac?
Not directly. iMacs don't have an HDMI input. A USB capture card plus a viewer app can show HDMI on the iMac, but that is a different thing from an external monitor connection.
Does a capture card work with any iMac?
9to5Mac's guide uses an app that needs macOS 14 Sonoma, which officially means a 2019 or 2020 iMac. Other viewers may work on older iMacs; we have not tested them.
Is a capture card better than an app?
For a game console or other HDMI device, yes, because the source needs no software. For extending a Mac, an app over a cable usually gives a sharper, simpler setup.