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Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-14, 9:11 AM

Hello,

I am trying to run the following setup, but want to make sure what would be the best way to do it:

 

ThinkPad T450 + 2 external Dell monitors (2560 x 1440). The monitors have HDMI and DP ports.

The laptop has miniDP and VGA. 


Reading online, I think that HDMI (or DP) -> VGA will not support the resolution (2560 x 1440).

I could hardly find any miniDP To Dual HDMI Adapters and I am not sure whether this will work at all.

 

Anyone with experience on that, any advise? 

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Re: Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-14, 13:11 PM

 

Check if displays support display port daisy chaining. That's the only way to connect both displays w/o any additional HW like docks  or USB3 to DP adapters. 

 

You won't be able to convert analog signal (VGA)  to digital.  These adapters only support digital to analog.

 

 

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Re: Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-14, 14:44 PM
That was my thinking as well, but how do I check if that will work? I don't find such info in the specs.
The only option I have found (in eBay) was miniDP To Dual HDMI Adapter, but would that work?
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Re: Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-14, 15:33 PM

 

Check monitor's user guides. Only one monitor needs to support DP daisy chaining, e.g the Dell U2518D supports daisy chaining.

You'll  connect the monitor, which supports daisy chaining, directly to laptop's miniDP port. The 2nd monitor needs to  be connected to the  DP out port on first monitor.  You won't need any additional HW. Just two DP cables.

 

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Re: Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-14, 15:46 PM
I didn't know this is possible.
The 2 monitors are the same model - Dell U2518D 25'' IPS QHD. I could not find info on daisy chain for it. Will it work? If it does, how does the OS recognize that - as one or two monitors?
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Re: Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-14, 16:13 PM

yes it will work. It did work with my T460p and I see no reason why it should not work with a T450. AFAIK the ultra docks are connecting at least both digital displays via MST.

It's worth trying out. It won't  cost you anything but a few minutes of your time.

Download user's guide from dell.com/u2518d. Everything you'll need to set this up is explained there. Look for  MST (multi-stream transport). You'll need to enable MST on one monitor, the one first in chain which you'll connect to your thinkpad.

The U2518D has two DP in  and one DP out (for MST ) ports. 

 

 https://en.wikipedia.org/wiki/DisplayPort#Multi-Stream_Transport_(MST)

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Re: Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-15, 13:39 PM
Thanks for the idea - this has actually worked. Important note is that this only works via Display Port. Meaning: Laptop (miniDP) -> (DP) Monitor 1 (DP) -> (DP) Monitor 2.

Last question:
I also have T480 (from work) and I will often use it with the same monitors when working from home. Now the challenge is that the Daisy Chain (MST) seems to work only via Display Port. However, T480 has only HDMI and USB Type-C. Does anyone know of a work-around? I am surprised that so far there doesn't seem to be a way to make it work on T480, while it works on T450 (thx for the advise).
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Re: Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-15, 16:23 PM

yes it's a DP only feature. That's why I used the term  'display port daisy chaining''  :)

 

 

some USB-C ports support  DP as well. All you'll need is an UCB-C  to DP cable.

Important: this is not a universal rule, because not every USB-C port do provide DP signals. It could be 'just' an ordinary/simple USB port...

 

 

 

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Re: Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-15, 16:29 PM
Thanks for the input, I'll probably end up buying one of the adapters for USB-C which have HDMI etc and solve the problem with the 2 monitors for T480. My original concern was T450 which is now OK :)
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Re: Possible? - T450 with 2 ext.monitors (2560 x 1440)

2019-11-15, 16:57 PM

 

On T480 both USB-C ports do support DP. No need for HDMI. Use DP whenever possible.

You can get a USB-C to miniDP adapter and than disconnect the dp cable from T450 and connect it to the T480.

 

I guess it should also be possible to connect first monitor to both systems at the same time with DP.  Display has two DP inputs. Then you could switch with this monitor's input selector between both systems.  I'm not sure if the second monitor remains enabled on the  'not selected' system. I've never tried that.

 

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