9 ms·

Why does the M1/M2 only support one external display?

33 points by zekrioca 4y ago

lefrenchy 4y ago
I got bit by this on my 13-inch first gen M1. I have a three monitor set up, and didn’t check the specs because I assumed basically any laptop worth it’s salt today would support that. It’s honestly a pretty shitty product choice in my opinion. Will definitely hold off on upgrading until it natively support more displays.
- jurmous 4y ago
  It is possible to connect more screens through DisplayLink
  - goosedragons 4y ago
    Which is a compromised option with considerably worse GPU performance on that screen, possible compression artifacts and it's more expensive than just a USB C dongle or a HDMI cable.
ab_testing 4y ago
I think it is mostly to differentiate the air from the pro. Evey professional needs 2 display monitors and the air can't do that. The air is however perfectly capable of handling day to day coding tasks. If it supported 2 monitors, it would have effectively cannabalized the pro line.
- olliej 4y ago
  Did you actually look at the link, or simply decide that the only possibility is malicious? "Because Apple's display controllers are so fancypants that the M1 Max has more silicon dedicated to display controllers than CPU cores." or later in the thread: "One display controller is larger than 2 PCPU cores with enough to spare to cover the ECPUs too."
- jurmous 4y ago
  I code daily as a job and am perfectly fine with one external screen. So not every professional needs 2 display monitors.
  - fredley 4y ago
    I'm surprised too. Built in + one external is what I've had most of my career. For a brief period I had two external and it was hell because OSX would switch them round on every wake from sleep.
  - zimpenfish 4y ago
    I've been coding professionally since 1996 and I've used external screens for maybe 24 months of that (mostly pre-2000). Almost all of it has been single desktop screen or laptop.
  - varispeed 4y ago
    I had a moment in my career using 5 screens for development. Then I learned how to use virtual desktops and never even looked for a second monitor since.
  - olliej 4y ago
    Same, I can't stand multiple displays, and I spend a good amount time trying to adjust to it. I would always rather a single display to having to move my head around all the time. I do think for many folk laptops have a piss poor screen res so I can understand using an external display if you have the option in such a case, but still not two for software dev.
znpy 4y ago
I used to drive three external displays (3x24", 1920x1200@60hz) on my almost four years old dell latitude 7390, using the integrated intel uhd 620 chip. it's incredible that a modern macbook costing likely twice as my old work laptop (the latitude 7390) can only do so little... Oh and the latitude had a ton of ports.
- olliej 4y ago
  So the M2 MacBook Air has 2x the resolution, can drive a studio display as well (6.4x the pixels to drive as your external display, or around ~2x the pixels of your three display example) and that's a billion colours (/s lolololol marketing :D). The point it is driving substantially more pixels than your example even if those "aren't separate displays" - I'd be generally curious how many 6k/60hz displays your dell could drive as that would be a fairly good counter here. Otherwise your reference laptop comes in at 0.7" vs 0.44", which I suspect also limits the sockets on the laptop, even without Apple's hatred of ports. I'm looking at the clearance of the usb-c ports vs the non-usb-c ports (ignoring the huge power one) and then looking at clearance on the usb-c ports on the new Air, and I'm not sure that there is the clearance for them.
  - bradknowles 4y ago
    That doesn't help if the external display in question costs as much as a used car, and more than six times as much as the computer it's connected to. The big hi-resolution monitors are damn bloody expensive. Two external monitors, each of which have half the number of pixels, are still less expensive together than the laptop itself. Same number of pixels being pushed, but not supported on the hardware. That's a shame.
    - olliej 4y ago
      Two external monitors is still the exception, one external monitor is the exception. Why should apple be increasing the cost of hardware, or reducing the feature set, of hardware for everyone to support niche users? The more I read, the more I suspect that supporting 6k@60fps _requires_ that much hardware in their display controller. "Can drive any screen you plug in" is better than "Can drive a pair or two of low-mid end screens" as a feature to communicate with end users. Don't get me wrong, I get that some people use multiple external screens, and you _can_ get the bigger MacBooks (that support 2-3 6k@60Hz screens) or some cheap pc laptop - though that means sacrificing the over a billion colors (/s). But if your price sensitive windows machines continue to exist, and if the cost vs features favors lower price[] for you that's probably where you should go. * Let's be honest, game studios still target windows+consoles first, then maybe linux for some reason, and finally macOS. Also they apparently write so much assembly ARM isn't feasible (they do not).
garyclarke27 4y ago
The other incredibly annoying fault with Apple M1 and external displays is that you cannot control the volume of a high resolution display connected via USB-C. eg Philips Brilliance 499P a fantastic Ultra-wide display that I bought because I could not connect my previous 2 monitors.
- jeffreyames 4y ago
  Check out monitorcontrol. Think it works over usb-c in your case but not positive. https://github.com/MonitorControl/MonitorControl https://github.com/MonitorControl/MonitorControl
  - zekrioca 4y ago
    Very cool, thanks for suggestion (and for implementing it).
- lathiat 4y ago
  Try “Lunar” it lets you control brightness and volume using the system keys on most but not all monitors: https://lunar.fyi/ https://lunar.fyi/
frozencell 4y ago
I have two external Dell monitors, one M1 air mac bought in 2021, so only one works. I bought a dual HDMI plug but it's not supported. What cheap device (displaylink hub port?) would you suggest people like me to buy to connect the second monitor? At
akagusu 4y ago
Interesting how people see thistle as a problem to be understood and solved instead of a design choice. The answer here is so much simple than that. Pay more and you get more external displays, pay less and you get less external displays.
- olliej 4y ago
  Or you could look at the link, and see that you're talking out of your ass. For whatever reason Apple's display controllers are huge - bigger than multiple cores - and clearly there isn't random left over space on the die for another one without sacrificing something else. I get many people on HN hate the idea of Apple existing as a company, but it turns out it is possible for things to not be "Apple is evil, and everything that they do is malicious". Something like the studio supports multiple displays because - afaict - it's multiple complete SoCs glued together, so presumably also has the display controllers from each complete SoC it has.
Kukumber 4y ago
Isn't it because they are optimized for energy efficiency, and the more external display the more Watt you need (20W/display)? If you build a laptop, why optimize it for many external displays, that doesn't make sense, i want it to be optimized for laptop use, wich is what they did
- wmf 4y ago
  Obviously every feature you add to a chip consumes some power while it's in use, but I don't think that's the reason why Apple only put two outputs on the M1/M2. It's more likely to be cost and market segmentation.
  - olliej 4y ago
    Well, yes - most people buy products based on price, and from the thread it's obvious that additional display controllers would could far more would be reasonable given the overwhelming majority of laptop users don't connect 1 external display to their laptop, let alone two. What you're saying is not dissimilar to saying the reason that some machines have a single small budget low speed intel cpu & iGPU yet others have 4 Xeons and dual full-size discrete GPUs is market segmentation. It's technically accurate, but implies a malevolent removal of features to create a product.

33 points by zekrioca 4y ago

I got bit by this on my 13-inch first gen M1. I have a three monitor set up, and didn’t check the specs because I assumed basically any laptop worth it’s salt today would support that. It’s honestly a pretty shitty product choice in my opinion. Will definitely hold off on upgrading until it natively support more displays.

jurmous 4y ago
It is possible to connect more screens through DisplayLink
- goosedragons 4y ago
  Which is a compromised option with considerably worse GPU performance on that screen, possible compression artifacts and it's more expensive than just a USB C dongle or a HDMI cable.

ab_testing 4y ago

I think it is mostly to differentiate the air from the pro. Evey professional needs 2 display monitors and the air can't do that. The air is however perfectly capable of handling day to day coding tasks. If it supported 2 monitors, it would have effectively cannabalized the pro line.

olliej 4y ago
Did you actually look at the link, or simply decide that the only possibility is malicious? "Because Apple's display controllers are so fancypants that the M1 Max has more silicon dedicated to display controllers than CPU cores." or later in the thread: "One display controller is larger than 2 PCPU cores with enough to spare to cover the ECPUs too."
jurmous 4y ago
I code daily as a job and am perfectly fine with one external screen. So not every professional needs 2 display monitors.
- fredley 4y ago
  I'm surprised too. Built in + one external is what I've had most of my career. For a brief period I had two external and it was hell because OSX would switch them round on every wake from sleep.
- zimpenfish 4y ago
  I've been coding professionally since 1996 and I've used external screens for maybe 24 months of that (mostly pre-2000). Almost all of it has been single desktop screen or laptop.
- varispeed 4y ago
  I had a moment in my career using 5 screens for development. Then I learned how to use virtual desktops and never even looked for a second monitor since.
- olliej 4y ago
  Same, I can't stand multiple displays, and I spend a good amount time trying to adjust to it. I would always rather a single display to having to move my head around all the time. I do think for many folk laptops have a piss poor screen res so I can understand using an external display if you have the option in such a case, but still not two for software dev.

znpy 4y ago

I used to drive three external displays (3x24", 1920x1200@60hz) on my almost four years old dell latitude 7390, using the integrated intel uhd 620 chip. it's incredible that a modern macbook costing likely twice as my old work laptop (the latitude 7390) can only do so little... Oh and the latitude had a ton of ports.

olliej 4y ago
So the M2 MacBook Air has 2x the resolution, can drive a studio display as well (6.4x the pixels to drive as your external display, or around ~2x the pixels of your three display example) and that's a billion colours (/s lolololol marketing :D). The point it is driving substantially more pixels than your example even if those "aren't separate displays" - I'd be generally curious how many 6k/60hz displays your dell could drive as that would be a fairly good counter here. Otherwise your reference laptop comes in at 0.7" vs 0.44", which I suspect also limits the sockets on the laptop, even without Apple's hatred of ports. I'm looking at the clearance of the usb-c ports vs the non-usb-c ports (ignoring the huge power one) and then looking at clearance on the usb-c ports on the new Air, and I'm not sure that there is the clearance for them.
- bradknowles 4y ago
  That doesn't help if the external display in question costs as much as a used car, and more than six times as much as the computer it's connected to. The big hi-resolution monitors are damn bloody expensive. Two external monitors, each of which have half the number of pixels, are still less expensive together than the laptop itself. Same number of pixels being pushed, but not supported on the hardware. That's a shame.
  - olliej 4y ago
    Two external monitors is still the exception, one external monitor is the exception. Why should apple be increasing the cost of hardware, or reducing the feature set, of hardware for everyone to support niche users? The more I read, the more I suspect that supporting 6k@60fps _requires_ that much hardware in their display controller. "Can drive any screen you plug in" is better than "Can drive a pair or two of low-mid end screens" as a feature to communicate with end users. Don't get me wrong, I get that some people use multiple external screens, and you _can_ get the bigger MacBooks (that support 2-3 6k@60Hz screens) or some cheap pc laptop - though that means sacrificing the over a billion colors (/s). But if your price sensitive windows machines continue to exist, and if the cost vs features favors lower price[] for you that's probably where you should go. * Let's be honest, game studios still target windows+consoles first, then maybe linux for some reason, and finally macOS. Also they apparently write so much assembly ARM isn't feasible (they do not).

garyclarke27 4y ago

The other incredibly annoying fault with Apple M1 and external displays is that you cannot control the volume of a high resolution display connected via USB-C. eg Philips Brilliance 499P a fantastic Ultra-wide display that I bought because I could not connect my previous 2 monitors.

jeffreyames 4y ago
Check out monitorcontrol. Think it works over usb-c in your case but not positive. https://github.com/MonitorControl/MonitorControl https://github.com/MonitorControl/MonitorControl
- zekrioca 4y ago
  Very cool, thanks for suggestion (and for implementing it).
lathiat 4y ago
Try “Lunar” it lets you control brightness and volume using the system keys on most but not all monitors: https://lunar.fyi/ https://lunar.fyi/

frozencell 4y ago

I have two external Dell monitors, one M1 air mac bought in 2021, so only one works. I bought a dual HDMI plug but it's not supported. What cheap device (displaylink hub port?) would you suggest people like me to buy to connect the second monitor? At

akagusu 4y ago

Interesting how people see thistle as a problem to be understood and solved instead of a design choice. The answer here is so much simple than that. Pay more and you get more external displays, pay less and you get less external displays.

olliej 4y ago
Or you could look at the link, and see that you're talking out of your ass. For whatever reason Apple's display controllers are huge - bigger than multiple cores - and clearly there isn't random left over space on the die for another one without sacrificing something else. I get many people on HN hate the idea of Apple existing as a company, but it turns out it is possible for things to not be "Apple is evil, and everything that they do is malicious". Something like the studio supports multiple displays because - afaict - it's multiple complete SoCs glued together, so presumably also has the display controllers from each complete SoC it has.

Kukumber 4y ago

Isn't it because they are optimized for energy efficiency, and the more external display the more Watt you need (20W/display)? If you build a laptop, why optimize it for many external displays, that doesn't make sense, i want it to be optimized for laptop use, wich is what they did

wmf 4y ago
Obviously every feature you add to a chip consumes some power while it's in use, but I don't think that's the reason why Apple only put two outputs on the M1/M2. It's more likely to be cost and market segmentation.
- olliej 4y ago
  Well, yes - most people buy products based on price, and from the thread it's obvious that additional display controllers would could far more would be reasonable given the overwhelming majority of laptop users don't connect 1 external display to their laptop, let alone two. What you're saying is not dissimilar to saying the reason that some machines have a single small budget low speed intel cpu & iGPU yet others have 4 Xeons and dual full-size discrete GPUs is market segmentation. It's technically accurate, but implies a malevolent removal of features to create a product.