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ZloyKrys
Paper Tape
Posts: 3
Registered: ‎04-12-2017
Location: US
Views: 21,454
Message 1 of 15

T470 and two 4k external monitors via Thunderbolt

I tried to ask on Reddit but it looks like nobody knows the answer. trying it here Smiley Happy

 

where could I find a confirmation that the T470 with onboard HD 620 graphics can drive two 4K Dell P2415Q at 60Hz monitors when connected via Thunderbolt? PSREFs just say it can support up to 3 displays (which is cool, but at what resolution and what will be the refresh rate) and max resolution supported is 4K at 60Hz (again, great, but how many of them?)

I was planning to use either the Startech's Thunderbolt 3 to Dual DisplayPort Adapter or Dell TB16 dock to connect the monitors, as Lenovo is not providing ways to connect two 4K monitors over the DisplayPort

Ideally, I'd love to have a dock which can connect both monitors but as I understand current generation of mechanical docks does not allow to use two 4k monitors, I guess it has something to do with bandwidth of chips used for DP ports in the docks.

nphd
What's DOS?
Posts: 2
Registered: ‎05-02-2017
Location: US
Views: 21,268
Message 2 of 15

Re: T470 and two 4k external monitors via Thunderbolt

I have the same question, but I'm planning on driving them via DisplayPort 1.2 with the ultra dock.

ZloyKrys
Paper Tape
Posts: 3
Registered: ‎04-12-2017
Location: US
Views: 21,263
Message 3 of 15

Re: T470 and two 4k external monitors via Thunderbolt

According to https://support.lenovo.com/au/en/solutions/pd029622#5 the UltraDock can only support ONE display 3840 x 2160 @60Hz via either DP1 or DP2. Unless Lenovo have an update to that matrix, the only way to connect TWO displays would be through Thunderbolt 3

nphd
What's DOS?
Posts: 2
Registered: ‎05-02-2017
Location: US
Views: 21,036
Message 4 of 15

Re: T470 and two 4k external monitors via Thunderbolt

I've done some more digging and I'm beginning to conclude that the TB3 port on the T470 doesn't have enough lanes to drive the dual 4K monitors from the single port. It looks like the latest X1 Carbon and Yoga should be able to, but not through Lenovo's own Thunderbolt 3 dock without daisy-chaining.

 

https://support.lenovo.com/us/en/solutions/pd029622

buschdin84
Blue Screen Again
Posts: 21
Registered: ‎11-06-2015
Location: DE
Views: 20,633
Message 5 of 15

Re: T470 and two 4k external monitors via Thunderbolt

Did anyone get it up, two external Monitor on the Stardock Dual Displayport-Adapter?

 

I have received today my T470 and only one Monitor is working. The second external monitor ist not vissible. That totaly unacceptable, because i give lenovo a change and try to move from Dell XPS 15 (9560) to the T470..but withouth the option to use two external Monitor with the Stardock Adapter, Lenovo can take back this crap Notebook!

bendicion
Ctrl-Alt-Del
Posts: 15
Registered: ‎11-20-2010
Location: US
Views: 20,605
Message 6 of 15

Re: T470 and two 4k external monitors via Thunderbolt

Looking at the guideline at https://support.lenovo.com/us/es/solutions/pd029622 the T470 supports two 4k external displays just fine — at a 30hz refresh rate. This is consistent with Lenovo’s marketing literature for the T470, which states that “you can even output to two 4K displays with the Thunderbolt Dock.” To get two 4k displays at a 60hz refresh rate would require an X1 Carbon 5 or an X1 Yoga 2, but 2x4k is fine at a 30hz refresh rate.

 

Point being, gamers and other niche setups which need a 60hz refresh rate will have to do with having only one external monitor; since the T470 is a business computer, not a gaming laptop, I think its target market normally only needs to have a 30hz refresh for two external 4k monitors running at the same time.

 

 

buschdin84
Blue Screen Again
Posts: 21
Registered: ‎11-06-2015
Location: DE
Views: 20,597
Message 7 of 15

Re: T470 and two 4k external monitors via Thunderbolt

The Problem is that Lenovo use an old, only with half Specs, TB3 Controller (JHL6240, 15BF), so that ,maybe the Lenovo Dock can be used with two external Display, but NOT THE STARTECH TB3 to Dual DISPLAYPORT Adapter, a generic Hardware Addon.

 

i also dont talk about 4K Monitor, i talk about two external Monitor in general and with the Startech TB3 to Dual DP, only one monitor is working (depending which was plugged in at first).

 

but have sold the T430 yesterday, so i am not longer frustreded about this, but i think it is important to warn other customer about this!

bendicion
Ctrl-Alt-Del
Posts: 15
Registered: ‎11-20-2010
Location: US
Views: 20,581
Message 8 of 15

Re: T470 and two 4k external monitors via Thunderbolt

I also think it depends on the dock being used. There is a report on Reddit (so, yes, take it with a grain of salt) that one can have two 4k@60hz displays by hooking up the Thunderbolt 3 to an external GPU: https://www.reddit.com/r/thinkpad/comments/648y1u/t470_akitio_node_two_4k60hz_two_1200x192060hz/

 

Also, a Reddit poster claims that the JHL6240 controller can be configured to connect to two or four PCIe lanes:  https://www.reddit.com/r/thinkpad/comments/5ykwge/to_all_owners_of_thinkpads_with_thunderbolt_3/ There are a couple of different posters who claim to have seen four PCIe lanes: https://www.reddit.com/r/thinkpad/comments/5ykwge/to_all_owners_of_thinkpads_with_thunderbolt_3/devs... https://www.reddit.com/r/thinkpad/comments/648y1u/t470_akitio_node_two_4k60hz_two_1200x192060hz/dg2p...

 

Since all of the above references come from Reddit, where the rule is “pics or it didn’t happen”, I have gone to the trouble of running HWiNFO64 on my T470; since I don’t have a Thunderbolt 3 device handy, all I can say is that there’s a 4x PCI lane which might be the Thunderbolt port, as well as a 2x PCI lane which might also be the Thunderbolt port.

buschdin84
Blue Screen Again
Posts: 21
Registered: ‎11-06-2015
Location: DE
Views: 20,572
Message 9 of 15

Re: T470 and two 4k external monitors via Thunderbolt

Did you read the last Posting, before you write your next?

 

You talked as reply to my Post, about 4k Display

 

I dont write about 4k Display, i have written general about two external display

 

 

I have also written about the StarTech TB to Double Displayport Adapter, if you dont know this, please try a seach before Posting again, because you can not compare an external gpu case with a dedicated gpu inside to ta TB Displayadapter. 

 

So, i repeat it again, as the result of the Initial Post;

 

StarTech TB3 to Dual Displayport DONT work with two external Display with T470. The second Display was not recognized.  And theres no difference if you try two 4k Displays or two full HD Display. 

 

 

ZloyKrys
Paper Tape
Posts: 3
Registered: ‎04-12-2017
Location: US
Views: 20,132
Message 10 of 15

Re: T470 and two 4k external monitors via Thunderbolt

Ok guys, don't bother. The T470, T570 and T470s support only one DP 1.2 port and a single DP port has bandwidth only up to 1 x 4k @ 60Hz or 2 x 4k @ 30Hz through daisy chaining. Too bad, Lenovo, the competition, namely Dell do much better and support 2 ports in their business laptops

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