Use the iMac 2017 (27-inch 5K) as a monitor
Yes, the 27-inch 5K iMac from 2017 works as a full 5K monitor for another Mac, over one Thunderbolt cable with DisplayBridge, the app I develop. I use one myself, and it is the base model.
In short: the 2017 is the oldest 5K iMac that DisplayBridge supports, the cheapest one on the used market, and even the smallest configuration is fast enough.
The iMac 2017 in facts
| Full name | iMac (Retina 5K, 27-inch, 2017), model number A1419 |
|---|---|
| Display | 5120 × 2880 pixels, 500 nits, wide color (P3) |
| Thunderbolt ports | Two Thunderbolt 3 (USB-C) ports on the back |
| Last macOS | macOS 13 Ventura |
| DisplayBridge | Tested, works: full 5K at 60 Hz, with sound |
| AirPlay to Mac | Can't receive it |
| Target Display Mode | No |
| Used price (eBay US) | Median $280; half of all working units sold between $220 and $350 |
What DisplayBridge is
DisplayBridge is a Mac app that turns one Mac into a display for another. You install the same app on the iMac and on the Mac you work on, connect the two with a Thunderbolt cable and click Connect. A few seconds later, the iMac shows up in System Settings as a second display. The picture arrives uncompressed at the full 5K and 60 Hz, the sound plays on the iMac's speakers, and when you disconnect, the iMac is a normal Mac again. It costs $29 once after a free 7-day trial, and the iMac never needs a license.
Using the iMac 2017 as a monitor
The 2017 is the oldest 5K iMac that works with DisplayBridge, because it is the first one with Thunderbolt 3 ports. Its last macOS, Ventura, happens to be exactly the version DisplayBridge needs. With the app on both Macs and one Thunderbolt or 40 Gbit/s USB-C cable in one of the two ports on the back, the iMac becomes a second display of your MacBook, Mac mini or Mac Studio, at the panel's full 5K resolution and 60 Hz.
You don't need a fast configuration. Mine is the base model: 3.4 GHz quad-core Core i5, 8 GB of RAM and a 1 TB Fusion Drive. DisplayBridge runs smoothly on it, because the iMac only receives the picture and shows it; the work happens on the other Mac.
The 2017 can't receive AirPlay, which only works with a 2019 or newer iMac, and like every 5K iMac it never had Target Display Mode. So the ways to use it as a monitor are DisplayBridge over a cable, or a hardware conversion kit if you want to connect a Windows PC or a game console. The step-by-step guide shows the setup with screenshots.
What a used iMac 2017 costs
In the last three months, working 27-inch 5K iMacs from 2017 sold on eBay in the US for a median of $280; half of them went for between $220 and $350, depending on the configuration. On local marketplaces such as Facebook Marketplace, you can sometimes find one for less than $200; I bought mine used for less than 200 Swiss francs. The 2019 model sells for about $500 and the 2020 model for about $700, with a display of the same class.
Even at eBay prices, that is far cheaper than any new 5K monitor, and you get a 5K display in an aluminium housing that still looks good on a desk.
What to check before you buy
A used 2017 iMac is a good deal, but check these points before you pay, ideally in person with the iMac switched on.
The iMac itself
- Both Thunderbolt ports work. DisplayBridge uses one of the two Thunderbolt 3 ports on the back. The best test is to bring your Mac and a Thunderbolt cable, install DisplayBridge on both (the trial is free) and connect them on the spot. Otherwise, plug a USB-C device into each of the two ports and check that the iMac recognizes it.
- No pink or reddish edges. Some 5K iMacs develop a pinkish, reddish tint along the edges of the screen. It is best known from the 2015 model, but some 2017 units have it too. It shows on white backgrounds and can get stronger once the iMac is warm, and the only known fix is a new display panel. Open a plain white image full screen after the iMac has been on for a while and look at the edges straight on. A faint tint that you only see from the side is normal.
- No lines, spots or cracks on the screen.
- It starts up normally. Base models have a Fusion Drive or a hard disk. That is slow but fine for a display, as my own base model shows; a failing drive, however, means the iMac no longer starts. Let it start up from off and run First Aid in Disk Utility.
Locks and company management
- Signed out of the Apple Account, Find My off. The seller should sign out of their Apple Account in System Settings, which also turns off Find My, and then erase the iMac. If Find My stays on, the previous owner can lock the Mac remotely with a passcode. The 2017 iMac has no Activation Lock in hardware (that needs the T2 chip of the 2020 iMac and the iMac Pro), so this sign-out is what matters.
- No company or school management. Many used Macs come from companies or schools.
If the iMac is still registered with the organization's device management (MDM), a
Remote Management screen appears during setup, and the organization can configure
it again after every erase. In Terminal, the command
profiles status -type enrollmentshould report "MDM enrollment: No" and "Enrolled via DEP: No". Only the organization can release it, so don't buy one that is still enrolled. - No firmware password. On Intel Macs, a firmware password blocks starting from Recovery or another disk. Restart the iMac while holding Command-R: if a padlock with a password field appears instead of the Recovery screen, the seller has to remove the password first.
- The serial number matches. Compare the serial number in About This Mac with the one on the underside of the stand and, if the seller has it, on the receipt. Apple's coverage check shows the exact model for a serial number.
The easiest way to cover the locks: ask the seller to erase the iMac and reinstall macOS, then go through the first setup screens yourself. If no Remote Management screen appears and you can create your own user account, the iMac is free to use. The configuration hardly matters: the base model is enough.
Prices: eBay US sold listings, condition "Used", July to October 2026, without listings for parts, damaged or locked units, and without sellers with no positive feedback. Checked on 11 October 2026.
Questions about this
Is the base iMac 2017 fast enough to work as a monitor?
Yes. Mine is the base model with a 3.4 GHz quad-core Core i5, 8 GB of RAM and a 1 TB Fusion Drive, and DisplayBridge runs smoothly on it. As the display, the iMac only receives the picture and shows it, which needs very little power.
Can the iMac 2017 receive AirPlay from another Mac?
No. Using a Mac as an AirPlay display requires an iMac from 2019 or later, or an iMac Pro. The 2017 iMac can send AirPlay, but not receive it, so DisplayBridge over a cable is the way to use it as a display for another Mac.
What is the pink edge problem on 5K iMacs?
Some 5K iMacs develop a pinkish or reddish tint along the edges of the screen, most often the 2015 model, but some 2017 units too. It is most visible on white backgrounds and can get stronger as the iMac warms up. There is no repair program for it; owners report that only a new display panel fixes it. When buying used, check the edges on a white screen after the iMac has been running for a while.
How do I check that a used iMac isn't locked or managed by a company?
Make sure the seller has signed out of their Apple Account, which turns off Find My, and erased the iMac. During the first setup, there must be no Remote Management screen; in Terminal, profiles status -type enrollment should report No for both MDM enrollment and DEP. On Intel iMacs, restart while holding Command-R: a padlock asking for a password means a firmware password is still set. On the 2020 iMac and the iMac Pro, also check that System Information shows Activation Lock Status: Disabled.
Which macOS does the iMac 2017 need for DisplayBridge?
macOS 13 Ventura, which is also the last macOS Apple released for the 2017 iMac. If yours is on an older version, update it to Ventura in System Settings before you install DisplayBridge.