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RockstarSR

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Mar 19, 2011
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I was following its launch for couple of weeks and it seems to be shipping now with same day shipping!

http://shop.lenovo.com/SEUILibrary/...de_menu_area=true&GroupID=460&Code=40AC0135US

The most interesting aspect of this dock is its support for 3 external displays. I haven't come across any other dock (already released or announced to be released soon) which supports 3 external displays out of the box.
  • 2 DisplayPort ports
  • HDMI
  • VGA
  • 5 USB 3.o ports
  • Gigabit Ethernet
  • 3.5mm headphone jack
  • Thunderbolt 3 port
Only bummer is the lack of SD/MicroSD slot and relatively slower charging (I believe it charges laptop at 65W; need to confirm it).
Lenovo's support confirmed that it is completely compatible with the new 2016 MacBook Pros.

Hope to see some reviews of it soon..
 
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dyn

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The most interesting aspect of this dock is its support for 3 external displays. I haven't come across any other dock (already released or announced to be released soon) which supports 3 external displays out of the box.
I think it supports 3 types of display connections, not 3 displays because Thunderbolt 3 only has 2 DisplayPort streams and thus is not able to support more than 2 displays. The 3rd display has to be connected via USB which affects performance negatively. That's usually a reason for manufacturers not to do it.

Btw, the dock is no longer listed on the website, maybe temporarily.
 

RockstarSR

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Original poster
Mar 19, 2011
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I think it supports 3 types of display connections, not 3 displays because Thunderbolt 3 only has 2 DisplayPort streams and thus is not able to support more than 2 displays. The 3rd display has to be connected via USB which affects performance negatively. That's usually a reason for manufacturers not to do it.

Btw, the dock is no longer listed on the website, maybe temporarily.

It does support 3 external displays (1080p). But yes if you are talking about 4K+ res, I believe thunderbolt 3's limitation is 2 5K displays? I'm talking about capabilities of 15" 2016 MBP.
 

dyn

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This isn't about resolutions but about the amount of streams. Thunderbolt 1 and 2 only support 1 stream and thus can only connect 1 display. Thunderbolt 3 has 2 streams and thus can connect 2 displays. It doesn't matter if the resolution is 1080p, 1440p or 4k. You can't connect more than 2 displays to a Thunderbolt 3 dock via those streams. The 3rd one has to be connected differently which usually means some kind of built-in USB adapter.

The only thing that matters is the 5k resolution because current 5k displays use 2 DisplayPort connections which means that 1 5k display will use both of the available DisplayPort streams Thunderbolt 3 offers. This is also the reason why you can have either 1 5k display or 2 4k displays connected.

The 15" MBP is a tad bit different. Unlike the docks it comes with 2 Thunderbolt 3 controllers (docks only come with 1) which, unlike the 13" MBP, can run at full speed. This enables the MBP to drive 2 5k displays but doing so means that you can't connect any other device to the 2 remaining USB-C ports on the MBP. You also need to connect one to the left side and one to the right because one controller is only for the right ports and the other only for the left ports.
 

jimthing

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This isn't about resolutions but about the amount of streams. Thunderbolt 1 and 2 only support 1 stream and thus can only connect 1 display. Thunderbolt 3 has 2 streams and thus can connect 2 displays. It doesn't matter if the resolution is 1080p, 1440p or 4k. You can't connect more than 2 displays to a Thunderbolt 3 dock via those streams. The 3rd one has to be connected differently which usually means some kind of built-in USB adapter.

The only thing that matters is the 5k resolution because current 5k displays use 2 DisplayPort connections which means that 1 5k display will use both of the available DisplayPort streams Thunderbolt 3 offers. This is also the reason why you can have either 1 5k display or 2 4k displays connected.

The 15" MBP is a tad bit different. Unlike the docks it comes with 2 Thunderbolt 3 controllers (docks only come with 1) which, unlike the 13" MBP, can run at full speed. This enables the MBP to drive 2 5k displays but doing so means that you can't connect any other device to the 2 remaining USB-C ports on the MBP. You also need to connect one to the left side and one to the right because one controller is only for the right ports and the other only for the left ports.

No, you can have two LG 5K's, plus use the other two ports (one on each side) at 40gbps for peripherals: docks, TB3 storage (like the new Pegasus3 (super expensive!) ones), just not another 4K/5K display.

FYI, the 15" MBP has 6 'display lanes' available: so each LG 5K takes 2 lanes, the MBP screen takes another lane, leaving a final lane available (I have had both a HDTV 1080p use that, or an 1440p 27" Apple Cinema (NOT Thunderbolt) Display – but it makes the MBP run loud and hot, from my testing).

I currently have 4 of the LG 5K's in my possession (2 made in 2016.12, 2 made in 2017.02) and am waiting to order a TB3 dock from one in this thread ("Which TB3 dock for your 15MBP?" https://forums.macrumors.com/threads/which-tb3-dock-for-your-15mbp.2028702 --> see analysis on pages 2 [text] + 3 [pix]!).
 
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dyn

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This isn't about PCIe lanes but about the amount of DisplayPort streams. Those are limited to 2 per controller (not per port!) which is why you have to connect one to the right and one to the left (each side has 1 TB controller). The other ports may indeed be used for additional non-display devices (good catch!). Apple has this to say about the 5k display (which explicitly tells you to connect one to the left and one to the right): Use the LG UltraFine 5K Display with your Mac.

Don't forget that the GPU also has to be able to drive all those displays and that the DisplayPort version supported by Thunderbolt is the actual limitation instead of the DisplayPort version supported by the GPU.
 

RockstarSR

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Original poster
Mar 19, 2011
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This isn't about PCIe lanes but about the amount of DisplayPort streams. Those are limited to 2 per controller (not per port!) which is why you have to connect one to the right and one to the left (each side has 1 TB controller). The other ports may indeed be used for additional non-display devices (good catch!). Apple has this to say about the 5k display (which explicitly tells you to connect one to the left and one to the right): Use the LG UltraFine 5K Display with your Mac.

Don't forget that the GPU also has to be able to drive all those displays and that the DisplayPort version supported by Thunderbolt is the actual limitation instead of the DisplayPort version supported by the GPU.


Honestly, I'm not sure why you are debating when Lenovo themselves have clearly mentioned in the dock's spec sheet that it can support 3 Full HD external displays and it supports new MacBook Pros.
 

jimthing

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This isn't about PCIe lanes but about the amount of DisplayPort streams. Those are limited to 2 per controller (not per port!) which is why you have to connect one to the right and one to the left (each side has 1 TB controller). The other ports may indeed be used for additional non-display devices (good catch!). Apple has this to say about the 5k display (which explicitly tells you to connect one to the left and one to the right): Use the LG UltraFine 5K Display with your Mac.

Don't forget that the GPU also has to be able to drive all those displays and that the DisplayPort version supported by Thunderbolt is the actual limitation instead of the DisplayPort version supported by the GPU.

Sorry, but what "other ports". The 15" tbMBP has FOUR TB3 ports. As I explained already, I have had TWO 5K's connected to the MBP (one either side), plus another ONE 1080p/1440p in one of the remaining two of the MBP's TB3 ports: it works.
Not great performance, but it does work, because of the 6x display lanes I previously explained.

Others have had TWO 5K's (one either side), with high-end TB3 Pegasus3 multi-RAID in one of the two remaining TB3 ports.

re. Lenovo's dock... Like all these docks thus far: one controller giving either TWO 4K's or ONE 5K.
 

dyn

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Honestly, I'm not sure why you are debating when Lenovo themselves have clearly mentioned in the dock's spec sheet that it can support 3 Full HD external displays and it supports new MacBook Pros.
That's because you don't get the entire point of the story so I'll repeat once more: Thunderbolt 3 only has 2 DisplayPort streams and therefor can only drive 2 displays max. That means the 3rd display has to be driven differently and that "differently" most likely is something like DisplayLink aka a USB adapter. They could have used 2 Thunderbolt controllers but that is a very expensive solution which no sane company would do in a dock like the one from Lenovo (you'd do that on docks that offer a lot more ports and other functionality which greatly benefits from having 2 controllers).

So your assumption that I'm debating against what the spec sheet mentions is plainly wrong. I'm actually explaining why it CAN drive all those 3 displays.

Sorry, but what "other ports". The 15" tbMBP has FOUR TB3 ports. As I explained already, I have had TWO 5K's connected to the MBP (one either side), plus another ONE 1080p/1440p in one of the remaining two of the MBP's TB3 ports: it works.
Exactly, on either side because those 5k displays require all the DisplayPort streams that are available (which are 2). This has been documented by Apple, Dell, Intel and many others. It's even in the official documentation on the official Thunderbolt website.

This is not a new limitation of Thunderbolt, it has been there since the beginning. Since the beginning we also had a way of working around it which is also officially documented by Apple, Dell, Intel and many others (especially dock manufacturers): you simply use another Thunderbolt device capable of injecting a DisplayPort stream. Or more simply put: you wanted to use 2 displays, then you had to connect 1 to the dock and the second to a second dock that is connected to the first. It also works with Thunderbolt displays (from Apple and LG) because they are no more than a display and dock in 1.

Not great performance, but it does work, because of the 6x display lanes I previously explained.
Stop the confusion! There are no display lanes at all. There are either PCIe lanes or DisplayPort streams. As you can see in the official documentation linked above, those 2 DisplayPort streams boil down to 8 PCIe lanes. Don't mix those up.

Others have had TWO 5K's (one either side), with high-end TB3 Pegasus3 multi-RAID in one of the two remaining TB3 ports.
Displays != storage devices and like I said, you can indeed connect all of them to the MBP at the same time.

You don't seem to understand Thunderbolt. Thunderbolt has always had a limitation when it comes to the amount of displays you can connect and still has that limitation. One not only needs to know there is a limitation but also fully understand it. As we've seen since Thunderbolt 1 most people have great difficulty understanding the latter. Manufacturers of docks have to continuously explain the limitation to customers even though it is clearly explained in their FAQ. So having to explain it here once more does not surprise me at all.
 
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jimthing

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That's because you don't get the entire point of the story so I'll repeat once more: Thunderbolt 3 only has 2 DisplayPort streams and therefor can only drive 2 displays max. That means the 3rd display has to be driven differently and that "differently" most likely is something like DisplayLink aka a USB adapter. They could have used 2 Thunderbolt controllers but that is a very expensive solution which no sane company would do in a dock like the one from Lenovo (you'd do that on docks that offer a lot more ports and other functionality which greatly benefits from having 2 controllers).

So your assumption that I'm debating against what the spec sheet mentions is plainly wrong. I'm actually explaining why it CAN drive all those 3 displays.


Exactly, on either side because those 5k displays require all the DisplayPort streams that are available (which are 2). This has been documented by Apple, Dell, Intel and many others. It's even in the official documentation on the official Thunderbolt website.

This is not a new limitation of Thunderbolt, it has been there since the beginning. Since the beginning we also had a way of working around it which is also officially documented by Apple, Dell, Intel and many others (especially dock manufacturers): you simply use another Thunderbolt device capable of injecting a DisplayPort stream. Or more simply put: you wanted to use 2 displays, then you had to connect 1 to the dock and the second to a second dock that is connected to the first. It also works with Thunderbolt displays (from Apple and LG) because they are no more than a display and dock in 1.


Stop the confusion! There are no display lanes at all. There are either PCIe lanes or DisplayPort streams. As you can see in the official documentation linked above, those 2 DisplayPort streams boil down to 8 PCIe lanes. Don't mix those up.


Displays != storage devices and like I said, you can indeed connect all of them to the MBP at the same time.

You don't seem to understand Thunderbolt. Thunderbolt has always had a limitation when it comes to the amount of displays you can connect and still has that limitation. One not only needs to know there is a limitation but also fully understand it. As we've seen since Thunderbolt 1 most people have great difficulty understanding the latter. Manufacturers of docks have to continuously explain the limitation to customers even though it is clearly explained in their FAQ. So having to explain it here once more does not surprise me at all.
Lol, what??

Try explaining more clearly, as you seem to contradict what I said I've actually done...??
 

dyn

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Things have already been explained clearly here, even linking to official documentation containing schematics and such. If you still do not understand all that information then apparently the discussion is over your head. Start by reading the official website, they have a lot of documentation where things are explained in laymen's terms which should get you going.

Btw, it is not me who is saying contradicting stuff, it is YOU who's doing that. You are contradicting the official Thunderbolt documentation from Intel. That plus some other things tell me that you do not have a good understanding of Thunderbolt itself. It's not like you can't do what you are doing, it's just that not everything can be done with Thunderbolt alone.
 

jimthing

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Yeah that's right I own loads of old/new Thunderbolt stuff used everyday, yet don't have clue while you do.

Condescending much... :rolleyes:
 

dyn

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Just wondering, but what makes you think that by owning a product that makes you an expert on the technology used in that product? The only thing it says is that you own the product.
 

jimthing

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Just wondering, but what makes you think that by owning a product that makes you an expert on the technology used in that product? The only thing it says is that you own the product.
I do know about the tech in the product – I have been talking about Tbolt tech across v1+2+3, even updating info on the wiki page accordingly, amongst others. When I use the term "display lanes" in my example, showing how I have actually had it work, you know, using the products concerned, I don't expect someone who clearly hasn't even tried, to come and tell me I'm somehow entirely wrong. But, yeah, thanks.
 
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MrX8503

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Each thunderbolt 3 controller has two streams (DP 1.2). This means you can drive a maximum of 2 monitors per TB3 controller.

Think of it this way, if you had a single DP 1.2 cable, how many monitors can you drive from it? Just 1.

The 15" MBP has TWO TB3 controllers, which gives it 4 streams (4x DP1.2) to drive nearly 30M pixels!
 

dyn

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When I use the term "display lanes" in my example, showing how I have actually had it work, you know, using the products concerned, I don't expect someone who clearly hasn't even tried, to come and tell me I'm somehow entirely wrong. But, yeah, thanks.
When you actually understand the technology you'd use the correct terminology and something that is a mix of 2 very different things that are used in the technology. It only adds to the confusion for those that do not understand. Again, (in Thunderbolt) there are either display streams or PCIe lanes. Display lanes do not exist.

When you actually understand the technology you'd post a response with the technical details instead of a personal attack which you've done. And that is rather disappointing to see from someone who is so highly of himself when it comes to understanding the technology. Instead of telling you understand it, how about you start showing it by responding on a technical level. Take the technical documentation I linked to and start showing us where the protocol allows for more than 1 5k display per controller for example. That works heaps better than repeating the "it works on my machine" responses you've posted thus far.

In other words: instead of personal attacks and bickering, how about educating us. After all, you have this great knowledge of Thunderbolt. Why not share it with the ones that do not have it? That's what this forum is about right? ;)
 

dyn

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Are you sure you've linked to the correct topic? Because all that is there from you are questions and a user review. There are no technical details.

To make it more clear: I'm not interested in "it works" posts but in the technical details on how it works.
 

jimthing

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Are you sure you've linked to the correct topic? Because all that is there from you are questions and a user review. There are no technical details.

To make it more clear: I'm not interested in "it works" posts but in the technical details on how it works.
Read through all 35 pages and all the sub pages and links. Search the internet for other Apple forums and articles, then get back to us about how you tested it with the 5K's with other displays you own. Then you can be certain you're sure.
 

dyn

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Never mind, the fact that you keep dodging the question and even are pointing to information from anyone but you speaks volume. Getting the technical information from you is a complete futile mission. I'll move my energy towards others that do have the knowledge and have no problem sharing it.
 

MrX8503

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Sorry, but what "other ports". The 15" tbMBP has FOUR TB3 ports. As I explained already, I have had TWO 5K's connected to the MBP (one either side), plus another ONE 1080p/1440p in one of the remaining two of the MBP's TB3 ports: it works.

The 15" MBP has 4x DisplayPort 1.2, which can drive 4x 4K, or 2x 5K @ 60hz. If you're running 2x 5K + 1440p, it's possible that one of your 5K monitors isn't running at the full 5K @ 60hz. I've also read somewhere that macOS will mis-report the resolution too. Can't verify that part though.
 

jimthing

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dyn

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The 15" MBP has 4x DisplayPort 1.2, which can drive 4x 4K, or 2x 5K @ 60hz. If you're running 2x 5K + 1440p, it's possible that one of your 5K monitors isn't running at the full 5K @ 60hz. I've also read somewhere that macOS will mis-report the resolution too. Can't verify that part though.
Exactly. This is a display that supports older TB2 Macs where it'll run at 3840x2160 or 3200x1800. TB2 only supports 1 DisplayPort stream. So either this display drops in resolution so it only uses up 1 DisplayPort stream or Apple has done a different way of wiring the ports where it is able to circumvent the TB3 controller and go into the GPU directly. The former seems more plausible than the latter.

@jimthing: last time: it isn't about whether or not it is working; as explained above this is a display that even works over a single DisplayPort stream (but it can't do 5k then) so it works even on older Macs that do not have TB3. What I requested from you and still am requesting is the technical explanation of it all since you claim to have knowledge of Thunderbolt because you own Thunderbolt products. It is not about proofing it works, it is about explaining how it works. Showing that something works is not showing you have actual knowledge of the technology.
 

jimthing

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Eh? I have provided the SYSTEM INFO panel, which clearly shows they are all running at full native resolutions.
 
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