Can it run a 1440p monitor? (Bonus: A funny convo with a Senior Supervisor)

Discussion in 'MacBook' started by realpras, Feb 22, 2017.

  1. realpras macrumors regular


    Oct 6, 2013
    Hi all,

    I have a 2016 MacBook and I'm thinking to get a Dell UltraSharp U2515H 25" Monitor (2560x1440p monitor).

    I will be using the HDMI port on the Apple Digital AV Multiport adapter.
    My question is: can it run the monitor on 1440p @60Hz using HDMI?

    I asked Apple Support via chat but a Senior Apple Advisor did not give me a definitive answer as he said he didn't want to provide misleading information.

    But then, he proceeded saying that USB-C and Thunderbolt 3 are the same thing. :)
    Is he correct or have I been mistaken so far to think that they're not the same thing?

    Screenshots are attached.

    Cheers, all!

    Attached Files:

  2. bill-p macrumors 68000

    Jul 23, 2011
    Well, he's sort of right. USB-C is the port, whereas Thunderbolt 3 is the technology behind it.

    But the same port can also be either a USB 2.0, USB 3.0, or USB 3.1 device as well. Thunderbolt 3 is just one of the "modes" available. This is more or less determined by the cable being used. So when you're buying USB-C cables, make sure to read very carefully on what "mode" the cable actually supports. A USB-C cable that only supports USB 2.0 mode, for instance, can't output to USB-C displays, but can still allow the device to charge, albeit maybe a bit slower.

    And then it also depends on your use case. For instance, if you're connecting your rMB 12" to a 4K display running at 60Hz, then any extra peripheral connected will run at USB 2.0 speed due to lack of bandwidth.

    That's basically saying... any 4K USB-C display that has a built-in USB-C hub will be pretty useless with rMB 12", and you're still better off using a separate USB hub.

    Anyway, to answer your previous question: yep, all rMB should support 1440p via HDMI, I think. 2016 rMB 12" may even support up to 2160p via HDMI 2.0, whereas it seems the 2015 model is limited to HDMI 1.4 (or at least that's what Intel has in the specifications, but I'm sure I read Apple mentioning the 2015 model supports HDMI 2.0 as well, they like to modify and slightly improve on the specifications like that).
  3. robvas macrumors 68030

    Mar 29, 2009
    I can't answer you for sure on the Dell, but I am running an Acer K272HUL and it works at 2560x1440 60hz using the Apple Digital AV adapter and HDMI cable. It also works if I use an HDMI to DVI converter and connect through the DVI port on the monitor. I have a 2015 MacBook 12"

    Best part is it also has DisplayPort, so I can connect it to my 2013 rMBP and Lenovo T450S as well!
  4. andy9l macrumors 68000

    Aug 31, 2009
    England, UK
    Definitive answer: yes.

    Your MacBook with the Apple USB-C AV adapter will drive a 1440p U2515H display at 60Hz.

    The Apple AV adapters only support HDMI 1.4, so it tops out at 1440p @60Hz, or 4K @30Hz. Or any other resolution/refresh rates that are mathematically equivalent.
  5. realpras, Feb 23, 2017
    Last edited: Feb 24, 2017

    realpras thread starter macrumors regular


    Oct 6, 2013
    but he says Thunderbolt 3 port is essentially just another name for USB-C port on a MacBook. By his understanding, it means the USB-C port on the 12'' MacBook is a 'Thunderbolt 3' port, which is inaccurate, right? And he said the adapter is a Thunderbolt 3, as far as I know it's just a USB-C and not Thunderbolt 3 (?) CMIIW
    --- Post Merged, Feb 23, 2017 ---
    Thanks for the responses, guys. Yes, it did work well :)

    However, I have a question. If my display arrangement is set as can be seen in the screenshot, is it normal that the Dock shows on the Mac and the apps open there, while the Primary display is the big display?

    This only happens in this particular arrangement and Dock position (on the bottom).
  6. ahostmadsen macrumors 6502a

    Dec 28, 2009
    You can move the dock to whatever screen you like. You hover the pointer near the bottom of the screen, and the dock moves there (although it's a little unreliable).
  7. bill-p macrumors 68000

    Jul 23, 2011
    Well, in a sense, he's right-ish, but not really. At least not when applied to the MacBook 12".

    What happens is that the MacBook 12" 2016 runs its USB-C port in a "pseudo-mode" that's close to Thunderbolt 2 but not quite. It would be more accurate to say it's USB 3.1 gen 2 with higher bandwidth.

    But it most definitely does not run its USB-C port in Thunderbolt 3 mode, because then that would allow the following:
    1) Connect to an external display and run full 5K resolution at 60Hz. This requires Thunderbolt 3 bandwidth because of the massive amount of data being sent.
    2) Connect to an external GPU like the Razer Core.

    But neither of those is possible because the port isn't really a Thunderbolt 3 (40gbps) port per se. It's only the MacBook Pro line in 2016 that run Thunderbolt 3.

    What the MacBook 12" 2016 has is a port that runs at USB 3.1 gen 2 (10gbps) regularly, and can kick it up close to Thunderbolt 2 (20gbps), which allows it to do 4K@60Hz (~16-18gbps) along with maybe 2-3 lanes of USB 2.0 (0.48gbps).

    Note that USB 3.0 specs require 5gbps throughput, and driving a 4K display sucks up enough bandwidth that you can guess the MacBook won't be able to provide USB 3.0 when connected to a 4K display.

    And that's a part of why I'm not holding out hope for the 2017 model if it's much the same. I'll wait for the next model after it that hopefully will come with Thunderbolt 3, because then IO speeds won't be borked anymore while connected to a 4K display. Processor performance be damned.
  8. realpras thread starter macrumors regular


    Oct 6, 2013
    It's actually USB 3.1 gen 1 not gen 2. And still he's not right-ish because he basically says USB 3 and Thunderbolt 3 are the same thing. By that logic, we can call the port on MacBook 12" as Thunderbolt 3.
    --- Post Merged, Feb 24, 2017 ---
    Yea, I'm aware of this gesture but the problem is the display stacked vertically so when you hover the bottom of the top screen, it just goes to the next screen below it. But eventually I manged to find out that the gesture can still be achieved by hovering on the sides that are not in the area of the bottom display, which can be configures in the Arrangement section on Display Sys Pref :)
  9. bill-p macrumors 68000

    Jul 23, 2011
    Yeah, that's the confusing part, so... allow me to clarify.

    USB 3.1 gen 1 is USB 3.0. There's no other way around it. It's simply a name change.
    USB 3.1 gen 2 is actually USB 3.1 by nature, and it has a few more changes that USB 3.0 didn't have. These changes were meant to compete against Thunderbolt 2 before Thunderbolt 3 was announced, and that USB-C would be the standard connector for Thunderbolt 3.

    Read this Wiki article about alternative mode to be "less confused"

    So to summarize, the USB-C connector in the MacBook can run in a number of modes. This is defined by the hardware controller and software.

    It's not as clear cut as saying "it's USB 3.1 gen 1 (USB 3.0)" or "it's USB 3.1 gen 2" or "it's Thunderbolt 3" because it can be whatever the hell it wants depending on the cable/hardware it's connected to, how the controller on the motherboard allows it, as well as software support from the OS and so on.

    Intel physically blocks the USB-C port on all Intel Core M computers such that if you connect a USB device to them, then they'll run at USB 3.1 gen 1 (or USB 3.0) specs or lower. That's why it's "only USB 3.1 gen 1".

    But... the device technically has more bandwidth than USB 3.1 gen 1. It can reach almost 20gbps, which is needed for DisplayPort 1.2 and HDMI 2.0 modes, which the USB-C port does support, but I suspect the extra bandwidth is reserved for display modes.

    I said "almost Thunderbolt 2" because the hardware needs to support that much bandwidth in order to support 4K @ 60Hz.

    Again, please refer to this Wiki article to understand what I'm talking about

    You can see 4K @ 60Hz requires a very gross amount of bandwidth. Up to 12gbps or even more (for higher color bit depth modes). If the USB-C port in the MacBook 12" is limited to USB 3.1 gen 1 @ 5gbps, then there is no way they'd be able to support 4K @ 60Hz, but they do.

    The decision to limit USB transmission speed to 5gbps (USB 3.1 gen 1 mode) is solely up to Intel and Apple, but again, the port needs to support higher than that. It has to be 18gbps to be compliant with DisplayPort 1.2 specifications.

    You can think of it this way: USB-C supports various standards (modes), Thunderbolt 3 was made specifically to work only with USB-C as the connector, so Thunderbolt 3 IS USB-C, but not vice versa. The USB-C port in the MacBook 12" is definitely not Thunderbolt 3, but it is definitely not just USB 3.1 gen 1 (USB 3.0) either.

    All of this confusion could have been avoided if Intel just flat out made the USB-C port in their Intel Core M specs able to deliver Thunderbolt 2. But they didn't. I'm guessing it's to reduce power consumption, but... whatever the case, the port is "almost Thunderbolt 2" and "is technically more than USB 3.1 gen 2", but for some reason, it's limited.
  10. curmudgeonette macrumors 6502

    Jan 28, 2016
    There's no blocking going on. The Core M chip used simply doesn't have a gen 2 capable USB controller.

    USB 3.1 gen 1 and DisplayPort 1.2 actually have quite comparable bandwidth - somewhere around 5Gbits/s per differential pair. The difference is that USB has a single transmit pair, and DisplayPort has four pairs.

    Don't think of USB-C as an electrical connection with a specific bandwidth. Instead, think of it as a big knife switch that switches the physical port between the USB controller, a DisplayPort source, a ThunderBolt controller, or other alternate mode devices. Getting back on topic, the "knife switch" in the rMB12 only switches between USB and DisplayPort.
  11. bill-p, Feb 24, 2017
    Last edited: Feb 24, 2017

    bill-p macrumors 68000

    Jul 23, 2011
    I don't think you quite understand what's going on here.

    What you call a "pair" is really "not that". But I feel like my words will not convince you, so here it is from someone else:

    What you are suggesting is that USB-C connects to separate USB controller and DisplayPort controller with separate "data lanes" (or "pair" as you put it), but that's not the case here.

    If there were separate controllers for USB 3.1 gen 1 and DisplayPort, then the DisplayPort controller won't be able to just "share" the data lanes of the USB controller just like that because the process would be very complicated. It would be simpler to have just one controller with access to all data lanes, because then it can dynamically allocate the data lanes as necessary. And that is exactly what we have here.

    The fact is that Intel Core M systems simply have just one USB-C controller that manages all of the data lanes all at once, and it allocates the data lanes as necessary depending on what "mode" it has it on. It's not a "big knife switch". It's just "one big knife".

    It seems confusing because we are used to having all of these different ports before, but now they are all in the same thing, and they are all sharing the same data lanes.

    The implication is there, though, as soon as you realize that the DisplayPort can influence data speeds of the USB ports: that Intel Core M systems have always had access to more bandwidth than whatever Intel allows them to use. However, for whatever reason (most likely power consumption?), Intel has "blocked" the USB-C controller from letting USB mode use the other data lanes, and DisplayPort (likely HDMI as well) mode has access to all of the lanes.

    The "knife switch" doesn't really "switch between" anything. It's "one big knife" being used for two different purposes all at once. Otherwise you can't have both USB and DisplayPort at the same time, or otherwise why would USB speeds be limited?

    Edit: also to note, since I don't think the article above has mentioned, but with my Lenovo ThinkVision X1 display, there is a switch that limits resolution to 1920 x 1080 @ 60Hz (effective bandwidth requirement for this is 3.2gbps, or about 4gbps), and that will allow USB 3.0 (which is, again, USB 3.1 gen 1) to be utilized for data transmission. So it's not as clear cut as saying "USB 3.0 needs all of the data lanes or otherwise you're forced to use USB 2.0" here. The MacBook does have more bandwidth than it looks.
  12. 3pp macrumors member

    Sep 30, 2014
    Whatever the answer is, you came across as a bit rude in that chat. He may be a 'senior advisor for Apple' but ultimately he's still a person who goes home every night and has a life. You're not talking to a robot.

    Perhaps instead of berating him for trying to help you, you could have politely informed him of his misunderstanding and left it at that? (I'm referring specifically to the point where you state you'd 'like to show your friend') Comes across as totally pompous.
  13. realpras thread starter macrumors regular


    Oct 6, 2013
    I realised I was a bit impolite to him but it was because he did not give me any answer if the adapter support 1440p @60Hz because he said he didn't want to provide misleading answer and this after he claimed it only supported up to 1080p @60Hz as per Apple product page. Then it turned to be funny to me when he said Thunderbolt 3 are what Apple called USB 3.0 on Mac. As per this discussion, he might be right-ish but the MacBook definitely didn't support Thunderbolt 3 so he was wrong but he insisted that he was correct. That's why I was messing around with him. And he was rude as well, he was the one who disconnected the chat without my confirmation. As far as I know, and from my experience so far, they always let the customers end the chat first or at least they will when both parties acknowledge that the chat should be ended.
  14. curmudgeonette macrumors 6502

    Jan 28, 2016
    I'm going to have to respectably say it is you who doesn't understand.

    Pair. Two wires using differential signaling to transmit a single bit wide data signal.

    A USB-C connector has 24 pins. Eight are power and ground, four are for housekeeping, two for the USB2 fallback when the cable is right side up, and two for the USB2 fallback when the cable is upside down. The remaining eight are grouped into four pairs. These are the interesting pins. When used for USB3, one of the four pairs is used for transmit, one for receive, and the remaining two are unused. Which two pairs are used and which two are unused depends on the cable orientation.

    The data lanes I am speaking about are on the USB-C connector, not internal signals on the logic board.

    (Of course, in today's computers many of the internal signals also use differential signaling on pairs of wires. But this doesn't matter in our discussion of the USB-C connector.)

    The Core M chip knows nothing about USB-C. The chip has a USB2 controller with multiple ports. It also has a USB3 controller with multiple ports. The USB2 and 3 controllers are entirely separate. It is up to the device driver in the OS to pair them into what the user perceives as a single port with both protocols. The Core M also has DisplayPort outputs. Finally, the Core M also has PCIe lanes, but those don't come into play in the rMB.

    In a mass market laptop without USB-C, the USB 2/3 ports would be connected in sets to USB-A connectors. One DisplayPort output would connect to the internal LCD, while another may connect to a DisplayPort connector.

    The "knife switch" in the 2016 rMB is a Parade Technologies PS8741A. As iFixit puts it, this is "likely an iteration of the PS8740 USB Type-C Redriving Switch." In the 2015 rMB, Apple used several jelly bean components to implement the same function.

    One "side" of the PS8741A connects to the USB-C connector. The other "side" connects to the Core M's USB3 and DisplayPort signals. Under software control, the PS8741A routes the interesting USB-C pins to various combinations of USB3 and DisplayPort, i.e. it is a crossbar switch, euphemistically a knife switch. It likely also handles cable inversion. "Redriving" means that it cleans up the signals to the proper voltage and timing specs so that they don't suffer cumulative degradation.

    Presently it appears that the PS8741 supports the following combinations:
    * USB3 in the right side up position and two unused lanes
    * USB3 in the upside down position and two unused lanes
    * USB3 in the right side up position and a half width (two lane) DisplayPort signal
    * USB3 in the upside down position and a half width (two lane) DisplayPort signal
    * A full width (four lane) DisplayPort signal for a right side up cable
    * A full width (four lane) DisplayPort signal for an upside down cable

    In all cases, USB2 is also available.

    In the 2016 MBP's, instead of the Parade chip, Apple uses an Intel Alpine Ridge chip. This adds the processor PCIe lanes into the mix of signals that can go on USB-C (with some protocol changes.) Interestingly, Alpine Ridge also has an internal USB3.1 gen 2 controller. This allows the MBP's to support gen 2 even though Skylake does not have gen 2!

    Alpine Ridge adds these combinations:
    * Four lane (two in, two out) ThunderBolt protocol for a right side up cable
    * Four lane (two in, two out) ThunderBolt protocol for an upside down cable

    ThunderBolt protocol encapsulates PCIe and DisplayPort.

    Once again, Core M knows nothing about USB-C. There is no limiting going on. USB3 is a protocol that uses four wires for data communication, two outbound, and two inbound. In a USB-A plug, it has just these pins plus the original USB2 connections (and an additional ground.) USB-C has more pins available, but USB3 cannot make use of them. Perhaps in the future there will be a USB4 that uses eight wires? Or maybe USB-C ports will start carrying two USB3 ports, but that would have issues with USB2 fallback?
    --- Post Merged, Feb 25, 2017 ---
    The rMB does not support an HDMI "alternate mode". That spec is too new. Instead, the multi media adapter converts DisplayPort into HDMI.

    If a future model does support HDMI alternate mode, that will be limited to HDMI 1.4 due to the number of pins available. An active conversion from DisplayPort will still be needed for HDMI 2.
  15. duervo macrumors 68020


    Feb 5, 2011
    "Oh my god are you kidding me."

    They were wrong, and they aren't perfect (I've recently had a similar experience with them,) but that statement from you changed the entire exchange.

    I'm surprised they kept things going for as long as they did, and equally surprised that they ended it as politely as they did. So, given the circumstances, hat's off to that Apple Support person.

    You should have just politely said, "Thanks," and ended the chat at that point, instead of saying "oh my god are you kidding me". Then, when you got the Support survey email later on, filled it out and provided your feedback there, so that maybe (hopefully) something can actually been done to improve things. (But personally, part of me suspects that those surveys end up in a waste pile of Dharma Initiative note capsules on the island in "Lost".)
  16. realpras, Feb 26, 2017
    Last edited: Feb 26, 2017

    realpras thread starter macrumors regular


    Oct 6, 2013
    one thing that irked me at that time is that he said he didn't want to provide misleading information (even if he said before with an affirmative tone that 60Hz is supported only up to 1080 - which is wrong, but I can understand because that was stated on Apple's product page for the product), but then he stated a wrong information after that.

    If he really meant not to give misleading information, he should've acknowledged that he was wrong and apologise because he did something he wasn't supposed to do, but instead, he kept saying that Thunderbolt 3 and USB 3.1 are the same.

    I realise I could've been more polite but the conversation before the screenshot already put a bitter taste about this particular guy, and I was polite to him when we were talking about the 1440p @60Hz topic, but that's that.
  17. Chub macrumors member

    Mar 26, 2013
    Just thought I'd chime in here as I use the same monitor, Dell U2515H, over HDMI and it works fine at native resolution (1440P@60Hz). The only thing I remember having to configure was getting the display to display RGB versus YCbCr - something to do with macOS thinking it's a TV.
  18. deuxani macrumors 6502


    Sep 2, 2010
    Maybe a little off topic, but what kind of changes did you make? I have a MacBook 2016 and the U2515H and everything looks great out of the box. Could it look even better then?
  19. Chub macrumors member

    Mar 26, 2013
    To be honest it wasn't as much of a change as I was expecting, and in all honesty it's a bit of a hack to get it to work anyway. If you're interested you can take a look at the "fix" here If you're already happy with it, it may not be worth doing.

    If you open the on-screen display for the monitor and go to color, you'll probably see that the input color type is set to "YPbPr". If you try changing to "RGB" without the hack you'll probably get some weird purple/green colours.
  20. realpras thread starter macrumors regular


    Oct 6, 2013
    Tftcentral shared the icc profile after they calibrated their display. Note that every individual display is different so the profile might not suit yours. You can find the profile here and search U2515H
  21. deuxani macrumors 6502


    Sep 2, 2010
    That hack sounds a bit like something I'm not looking forward to running :) My colour profile says "HD 709-A". If I click "Show profiles for this display only" it will show "HD 709-A" and "SD 170M-A". I've read that HD 709-A should be OK, but if there is an obvious improvement, I'm willing to try it. The colours look good on the Dell, but in Notification Center the big ultra light font don't seem that sharp.

    I might give that a try, thanks.

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