Hacker News Reader

Comment by bklyn11201 | Hacker News Reader

> "which points to the problem I’d have if I wanted to update my own five-year old iMac, I’d need to jettison a perfectly good display in order to move to an Apple Silicon CPU."

Is it impossible to use the 27" iMac as a display monitor for the new Mac Studio?

View on HN

Target Display Mode which turns iMacs into monitors is not supported on newer iMacs (anything post 2015):

https://support.apple.com/en-us/HT204592

This sounds terrible for the consumers and for the environment as once the computer inside dies or is obsolete, you have to throw away a perfectly good display that could have a second life as an external monitor plugged into a more modern system since display technology doesn't go outdated as fast as computing.

As someone who finally bit the bullet and scrapped/curbed 2 old iMacs, yeah. It hurt a lot. Perfectly good, well-calibrated 21.5” and 27” monitors just reduced to paper weights. Plucked the ram/HDD’s and sent them on their way. I looked into every possible option for them. Such a waste.

Especially a waste since it's even the same panel as the one you're throwing away. Apple hasn't upgraded the 27" 5k for 8 years now, this new one included (lots of non-display upgrades like the camera and audio, sure, but the display itself hasn't changed)

27” 2.5K actually (should’ve specified). It was a mid-2011 iMac. The 21” was a 2009 (belonged to a sibling).

It's terrible. The original reason Apple dropped this feature was because there wasn't an external bus that could push that many pixels. But Thunderbolt can do it now. This reuse would be more meaningful than preconsumer recycling of aluminum.

I use https://astropad.com/product/lunadisplay/ to use my iPad or an old Mac's screen as a secondary screen and it's good.

Well this is upsetting. I just scrapped and curbed 2x iMacs like 2 months ago because they couldn’t do anything anymore. This would’ve been perfect.

Wouldn’t an obsolete computer still be perfectly fine for less demanding users? Average Joes, poor people, a kid’s first PC, etc. — give it away, I say.

Depends on how old. My sisters old iMac ran perfectly fine but couldn’t load 75% of the internet unfortunately and most of the apps couldn’t be updated past a 5-6 year old build.

"You can use more than one iMac as a display, if each iMac is using a Thunderbolt cable to connect directly to a Thunderbolt port on the other Mac (not the other iMac)."

Do Mac's not have USB ports? It's truly bizarre that you need 1 thunderbolt port per monitor. That's an incredible amount of wasted bandwidth.

How is a USB port from pre-2015 going to help you transmit a DisplayPort signal?

Good point.

They've never supported target display mode for any of the 5k iMacs. 5k displays, in general, seem to be few and far between, and poorly supported (haven't seen a single one for PC, only Apple's offerings), so I imagine trying to support target display mode wouldn't be great.

I remember reading at the time that they couldn't reasonably get the connector throughput working. The original 5K iMacs used custom high bandwidth internal interconnects because there weren't any standard spec interconnects that could do the job, therefore no commercial external cables or connectors up to it either.

It might be possible in theory now, but I suppose that ship has sailed.

There are workarounds, like "Luna Display" (I haven't tried it and I'm not affiliated).

I also wonder how well running something like a VNC client fullscreen on the old iMac with universal control might work. (I've also used Jump Desktop's "Fluid" protocol which is the same general idea as VNC, though provided a higher-quality lower lag connection in my case.)

I think there are some decent solutions for a secondary display, but I kind of doubt any of these would be good enough for a primary display for most use cases.

I would guess all of these have tradeoffs in terms of lag, frame rate, quality, reliability, etc. though I'd love to hear different.

This used to be possible on older iMacs and was called Target Display Mode. I believe a five year old iMac is too recent to be able to do it.

DIY display from the hardware should be possible with a display driver from Aliedpress, though.

I looked around for something like this but finding something that can drive the panel is tricky. In my case it was an old surface studio with a 3000x2000 resolution. I think it’s actually two panels fused together and calibrated at the factory and it’s all custom. Finding a board seemed nigh impossible

I believe they got rid of target display mode support a number of years ago, in terms of both a hardware and software (High Sierra or earlier only)

My late 2009 27” iMac can be used as a monitor by connecting a laptop to the minidp port. I doubt this is still possible in newer Macs after 2015.

Target display mode exists but it’s compatibility support could be improved.

It's impossible to use it as a display for anything than itself.

Target display mode has been dead and gone since 2015.

yeah i was very disappointed to find out i couldn't use my wife's imac as a display for my mpb

Reply on news.ycombinator.com