4k60Hz on 2016 Macbook - the issue is not USB 3

[Narcaz]

I had been beating that drum a year or so ago, but if you think about it, Apple has always marketed it's displays to the high end of the market, and in 2016, there wouldn't be many high end resolution-conscious pros interested in a 23.6" or 24" display. Hence, they declined to go this route (although I wish Apple would release a consumer level display in that size with a palatable price point - I think they'd sell a bunch of them). If anything, the existing Thunderbolt Display should have been updated in early-2013 with USB 3.0, updated MagSafe 2, iMac-like thinness, and laminated display. They could have at least sold that at $999 with somewhat of a straight face versus what they sell now.

Looking at other price increases and completely user experience killing decisions, a straight face isn't really a priority anymore. So far this whole shift towards retina/4K/5K/UHD display technology didn't work out as i hoped. From a company, which is highlighting retina screens at every keynote, i expected more than a few mixed messages. After the introduction of the rMBP in 2012, imo this progress slowed down too much. Btw. Apple offers a 4K video recording on the iPhone, but doesn't support 4K on the Apple TV (or via Lightning HDMI adapter). Where exactly should i enjoy those videos? Probably on a 4k/5k iMac with a spinner drive...

Is Kaby Lake officially out of the running for DisplayPort 1.3? I haven't been able to find anything definitive about that. If it did support it, there is a very very slim hope we could see Kaby Lake MacBook Pros at WWDC shipping during the mid-summer months along with a 5K Thunderbolt Display, but as you said, the more likely scenario is mid-to-late 2017 for that setup.

So far nothing official from Intel, but those leaked roadmaps suggested no dp 1.3 and no USB 3.1 Gen2.

Hmmm, so if the fanless enclosure is not the problem, and the Intel HD 515 GPU/Skylake combo supports 4K at 60Hz, and the MacBook's USB-C port has DisplayPort 1.2, than why on earth can it not do 4K at 60Hz? I'm truly surprised that port on the 2016 MacBook isn't Thunderbolt 3 considering Apple has been Thunderbolt's biggest backer since 2011. Shame. I can only theorize that they think buyers of this machine will have very little interest in external displays and super high speed data transfers so why stuff those in there when they are good upsell traits of the MacBook Pros.

zhenya explained the problem and the "negative" consequences very well. Although i tend to disagree about the minimalist vision as sole reason for this decision. Another reason could be up-selling people to a next gen rMBP for a while. Besides that Apple doesn't offer neither a compatible display nor special thunderbolt equipment (SSDs, eGPUs etc) and has currently more to lose (another heat source, less room for the battery, lower margin) than to gain from most of the targeted audience. And yet the lack is still a dealbreaker for me and i wish Apple included it somehow, if it that means adding a few extra grams and millimeters.

 

[PatriotInvasion]

??? I explained in great detail why the MacBook doesn't do 4K/60hz above. To do so over the single existing usb 3.1 port would limit anything else connected to that port to USB 2 speeds, and Thunderbolt would require an extra daughter-card which is not fitting in the minimalist vision of this notebook.

Sorry, you did. Been commenting on a few of these MacBook/4K related threads and lost track of the earlier portions of the discussion. Appreciate your detailed breakdown.
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Besides that Apple doesn't offer neither a compatible display nor special thunderbolt equipment (SSDs, eGPUs etc) and has currently more to lose (another heat source, less room for the battery, lower margin) than to gain from most of the targeted audience. And yet the lack is still a dealbreaker for me and i wish Apple included it somehow, if it that means adding a few extra grams and millimeters.

If a few extra millimeters and grams doesn't matter to you, you should be getting your wish with the upcoming MacBook Pros. Sit tight.

 

[lisag]

The 4K only @30Hz is an Apple thing. I've recently reviewed Windows laptops with a USB-C 3.1 Gen. 1 port (non-Thunderbolt 3) -- the Samsung Notebook 9 15", for example, and they do 4K @60Hz. The 2016 MacBook will not, even when using the same USB-C to DisplayPort 1.2 cable that does work @60Hz with the Windows laptops.

 

[zhenya]

The 4K only @30Hz is an Apple thing. I've recently reviewed Windows laptops with a USB-C 3.1 Gen. 1 port (non-Thunderbolt 3) -- the Samsung Notebook 9 15", for example, and they do 4K @60Hz. The 2016 MacBook will not, even when using the same USB-C to DisplayPort 1.2 cable that does work @60Hz with the Windows laptops.

What those devices won't do is transmit 4k/60hz while simultaneously providing usb 3.1 data speeds over the same cable, which makes single-cable docking a non-starter. Apple could indeed have added additional ports to provide simultaneous 4k/60hz video support and full speed usb 3.1. It's my opinion that they did not go this route however because of the comparative confusion it would have induced. The form factor would have needed to be changed to allow room for a standard usb port. If they offered two usb-c ports, single cable docking would have been possible while connected to anything other than a 4k/60hz display. If you were connected to a 4k/60hz display through one port, you'd have to connect to the second usb-c port in order to get reasonable usb speeds. How does one handle docking in this situation? It certainly would not have allowed them to sell a simple, single connection adapter such as most of us use for current docking needs.

The notebook 9 handles this by providing 3 different connectors which would be needed for docking - power, video, and usb. This is exactly what the rMB is designed to get away from.

 

[curmudgeonette]

The 2016 MacBook will not, even when using the same USB-C to DisplayPort 1.2 cable that does work @60Hz with the Windows laptops.

Interesting. The iFixit teardown shows a USB-C mux chip driving the port in the '16 rMB. It has a mystery part number, but there's a known chip that's just one digit off. That chip is capable of muxing four lanes of DP 1.2 out the USB-C connector. It is hard to imagine that Apple would have opted for a crippled version that only muxes two lanes of DP 1.2.

Perhaps this is just a software limitation that was overlooked. Or maybe Apple is intentionally limiting the capability in order to control heat generated in the rMB.

 

[zhenya]

Interesting. The iFixit teardown shows a USB-C mux chip driving the port in the '16 rMB. It has a mystery part number, but there's a known chip that's just one digit off. That chip is capable of muxing four lanes of DP 1.2 out the USB-C connector. It is hard to imagine that Apple would have opted for a crippled version that only muxes two lanes of DP 1.2.

Perhaps this is just a software limitation that was overlooked. Or maybe Apple is intentionally limiting the capability in order to control heat generated in the rMB.

If Apple had configured it such that all 4 lanes were available for DP 1.2, there would be no lanes left for high speed usb. As such, any docking adapter, such as the ones Apple sells, among many others, which combine usb and HDMI or other display-out ports, would be limited to USB 2.0 speeds in the case that a user connected a 4K/60hz display. Given that Apple does not even sell such a display, and by limiting DP to two of the four available lanes in the single USB connector they would create a much more consistent experience for the end user, it doesn't seem surprising to me why they designed it in this way.

 

[curmudgeonette]

If Apple had configured it such that all 4 lanes were available for DP 1.2, there would be no lanes left for high speed usb.

The point of a multiplexer chip is that the configuration is changeable: If the system detects Apple's charge/HDMI/USBA dongle, it can switch to two DisplayPort lanes, one USB3 Tx channel, and one USB3 Rx channel. If the dongle were flipped over, it'll be one USB3 Tx channel, one USB3 Rx channel, and two DisplayPort lanes using the pins that were USB in the previous example. If a simple USB3 cable is plugged in, it'll be TX and RX channels, and two unused pairs, configured depending on if the cable is "right side up" or "upside down". And finally, if it is a DisplayPort cable, it can configure to four DisplayPort lanes and no USB3 channels.

For some reason, apparently this last option is limited in functionality. Perhaps it is a software limitation. Maybe a thermal limitation. Maybe generic cables don't identify themselves correctly.

A useful experiment at this point would be to use a USBC to (Mini)DisplayPort cable to connect a DP1.1 display that maxes out the link. Such as the Apple Cinema Display. If it works, that will show that all four lanes can be used for DisplayPort output.

 

[zhenya]

The point of a multiplexer chip is that the configuration is changeable: If the system detects Apple's charge/HDMI/USBA dongle, it can switch to two DisplayPort lanes, one USB3 Tx channel, and one USB3 Rx channel. If the dongle were flipped over, it'll be one USB3 Tx channel, one USB3 Rx channel, and two DisplayPort lanes using the pins that were USB in the previous example. If a simple USB3 cable is plugged in, it'll be TX and RX channels, and two unused pairs, configured depending on if the cable is "right side up" or "upside down". And finally, if it is a DisplayPort cable, it can configure to four DisplayPort lanes and no USB3 channels.

For some reason, apparently this last option is limited in functionality. Perhaps it is a software limitation. Maybe a thermal limitation. Maybe generic cables don't identify themselves correctly.

A useful experiment at this point would be to use a USBC to (Mini)DisplayPort cable to connect a DP1.1 display that maxes out the link. Such as the Apple Cinema Display. If it works, that will show that all four lanes can be used for DisplayPort output.

I completely understand that it's changeable - my point is, Apple's vision for this device is everything is moved over that single cable. That means an adapter/hub/dock of some sort. What happens to the USB ports on that hub or dock when a 4K/60hz display is connected? They drop down to USB 2.0 speeds. It's not consistent for the end user (so ports on that dock that are labeled as USB 3 aren't necessarily always USB 3). Allocating up to 2 lanes for display and 2 for USB keeps things consistent for the end user, at the cost of some flexibility for the fringe users (connecting to monitors Apple doesn't even sell).

 

[PatriotInvasion]

I completely understand that it's changeable - my point is, Apple's vision for this device is everything is moved over that single cable. That means an adapter/hub/dock of some sort. What happens to the USB ports on that hub or dock when a 4K/60hz display is connected? They drop down to USB 2.0 speeds. It's not consistent for the end user (so ports on that dock that are labeled as USB 3 aren't necessarily always USB 3). Allocating up to 2 lanes for display and 2 for USB keeps things consistent for the end user, at the cost of some flexibility for the fringe users (connecting to monitors Apple doesn't even sell).

End of the day, this is just not the machine Apple envisions people buying and then dropping another $500-$1,000 on a high-end (and non-Apple branded) 4K/60Hz display. As you stated, maintaining consistency of the USB 3.1 Gen 1 data transfer speeds trumped the fringe desire to hook this MacBook up to a 4K display at 60Hz. For that setup, we just need to await the MacBook Pros that will very likely sport at least one Thunderbolt 3 port and one additional USB-C port. My guess is the trade-off in size/weight of a potential 13" MacBook Pro with the MacBook's design language and generally the size of a MacBook Air (or smaller) will be worth it for 4K display lovers.

That said, if the thinness and lightness of the 12" MacBook is so desirable, than there is a solution available today, albeit very expensive, that is even better than being able to hook it up to a 4K display. Just buy a 12" MacBook for portable use and a 5K iMac for desktop use. You don't even have to worry about a wire! If you consider the benefits of 5K vs 4K and the eventual resale value of a 5K iMac over a non-Apple branded 4K display, it really is an attractive option.

 

[curmudgeonette]

Apple's vision for this device is everything is moved over that single cable. That means an adapter/hub/dock of some sort. What happens to the USB ports on that hub or dock when a 4K/60hz display is connected?

But what if the user connects a display directly via a simple cable - no adapter/hub/dock? Then there are no USB ports to worry about. This is a valid use case: Imagine a business person who needs to give a presentation and the conference room has a 4Kx60Hz display. The presenter plans on running the MacBook on battery power, and using only the built in keyboard and trackpad for input.

For evidence that this is an intended use, consider that one of the dongles Apple offers has VGA. Who still uses VGA displays today? Answer - projectors! Like in a conference room.

at the cost of some flexibility for the fringe users (connecting to monitors Apple doesn't even sell).

This might be root of the issue! Apple doesn't sell such a monitor. So there's no corporate impetus to code/test/support such a configuration. (Gee, didn't this also happen with the nMP? It took a software update to support 4K displays to the ability of the hardware.)

 

[Narcaz]

(...) If a few extra millimeters and grams doesn't matter to you, you should be getting your wish with the upcoming MacBook Pros. Sit tight.

It seems a bit overkill to get a 13'' rMBP just for this feature. The extra CPU/GPU power and the fan isn't needed for my usage. And in contrast to a lot of the "thin and light as possible" posters, i doubt that an extra alpin ridge controller, a few wires, a bit more battery and slightly larger chassis would have completely destroyed the concept of the Macbook. It would be just a different laptop compromise.

What those devices won't do is transmit 4k/60hz while simultaneously providing usb 3.1 data speeds over the same cable, which makes single-cable docking a non-starter. Apple could indeed have added additional ports to provide simultaneous 4k/60hz video support and full speed usb 3.1. It's my opinion that they did not go this route however because of the comparative confusion it would have induced. The form factor would have needed to be changed to allow room for a standard usb port. If they offered two usb-c ports, single cable docking would have been possible while connected to anything other than a 4k/60hz display. If you were connected to a 4k/60hz display through one port, you'd have to connect to the second usb-c port in order to get reasonable usb speeds. How does one handle docking in this situation? It certainly would not have allowed them to sell a simple, single connection adapter such as most of us use for current docking needs.

The notebook 9 handles this by providing 3 different connectors which would be needed for docking - power, video, and usb. This is exactly what the rMB is designed to get away from.

Since when is simple docking a priority for most users?! Maybe for you, me and few others, but after reading a lot of posts around here, I think the 12''MB is a product for a wireless lifestyle. Most people are probably using some wireless storage solutions or cloud service and don't ever think about USB speeds. I mean i get your concern and personal preference, but this isn't such a big problem as you make it sound.

As curmudgeonette has written, a single purpose adapter could probably solve this. Or the MB could show something like a warning ("your usb speed is now reduced") when you select 4K/60hz. USB 2 speed is definitely not great in this scenario, but i don't see a problem for people, who only want an accompanying retina desktop display or show pictures/videos on their 4K TV, projector or whatever.

And about avoiding customer confusion: I think this ship has sailed. A lot of people have been confused about the lack of Apples Display support, about the whole USB C adapter compatibility (and why some aren't able to charge) and a lot of people will be confused about that all the upcoming TB 3 stuff for the next gen rMBP, which won't work despite having the same connector.