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Laptop UHD 620 Graphics with 2 QHD Monitors using HP G4 dock


I have a HP ENVY x360 - 15t-dr100 CTO laptop with Intel UHD 620 graphics. Laptop screen is FHD.

I plugged in an HP G4 Thunderbolt dock (but not thunderbolt connection) and works fine with 2 FHD Monitors. 

Tried using 2 QHD Monitors, only able to get QHD on one screen, but not on both, and one screen shows HZ as interlaced 


Any workaround?


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This may take a bit;

the Thunderbolt dock... cool

But it has its own firmware and its own drivers.

Make sure these are updated and HP provides the links.

The UHD 620 should handle it all.

Keep in mind it hsa it's own drivers and config...

The FHD's worked fine because the firmware within them is simpler and does not interfere.

I have a 32" Acer and a 27" Asus here and they are both UHD.... but the firmware and software is more complex.


Since I had to go through this myself I can tell you;

You have to get in the playground and tell all the boys to play nice together.

this is no tech guru book on configuring and calibrating display

it's just lessons learned by "seat of my pants" dealing with it having no support from anyone:


Shut off any added settings the UHD monitor might be trying to add.

Set everything to defaults and shut as much as you can off. (for now)


Second step: make sure the Thunderbolt is fully updated and not complaining or trying to introduce things you might not want.


Make sure the UHD 620 knows it's feeding a thunderbolt.

There should be something here at Intel for it but I havent searched for it yet.

The thing you need to keep in mind is the thunderbolt is "outside" your system so all the troubleshooters and support assistance stuff say it doesn't exist; it's not in your system.


HP, Lenovo, Dell, Acer... they are all good at supporting whatever they put in the box and sell you. But they did not sell you a thunderbolt.


In your case you got that covered... HP system to an HP thunderbolt...

You got 'em!


Intel might play nice and do it for you, but really you should get better results from HP.

If the HP comp doesn't know the thunderbolt it's because you haven't installed it yet.

But it sounds like you have... just double check in Device Manager.


At this point things can get awkward since your system knows it has to feed a display.

If it was left up to windows they would slap a generic driver on it from 2006 and spit out the 1's and zeros.


Put simply the Mboard goes to the operating system, the OS goes to the Graphics, and graphics goes to the monitor; (in your case insert thunderbolt before monitor). And now the UHD monitor might want a say in all of this.

You get to be the boss.  


That brings us to the present day, but you did not mention the manufacturer of the UHD's you plugged in.

Some have better support than others..


Something in the UHD monitor's firmware  is trying to run the show and can't. so it's going blank.


That's why I said at the beginning to shut the settings off and set all to defaults.

Let the system run the thunderbolt and let the thunderbolt run the monitors.

Then slowly re-introduce what the monitor can do and you should be ok. 


Most of what these UHD monitors can do I don't even use because I'm not a gamer.


It was Intel who showed me what I can do with the monitor after I let it identify my system.

So I turned on layering and I turned on sync.

Beautiful results, but Intel was running it, not the monitor. 



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Super User
The explanation for this issue is far simpler (he says sarcastically).
When you plug this dock into a basic USB-C port, one of the two USB-C transmission channels ends up being dedicated to the dock's USB hub. This leaves only one channel for DisplayPort and thus the available bandwidth is cut in half.
Now, UHD 620 supports DisplayPort 1.2, which means max. bandwidth is 17.28Gb/s. Half of this is 8.64Gb/s. Supporting one UHD monitor at 60Hz requires 5.63Gb/s. Supporting two requires, well, more than is available.
So, what to do? Well, if you force the first monitor to run at 30Hz, the second will also be able to run at 30Hz (the two would then only require 5.56Gb/s, which can be easily handled). Not optimal but hey, it works.
Hope this helps,
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Good stuff, it gave me something to work on.


That little Envy by default has 16 G of ram and a 12 core processor.

Everything in there is solid state.

It also has 2 thunderbolt ports.

And the 620 can manage it all.

If I was looking through the window and saw a guy trying to get a laptop to run it's own display and 2 QHD monitors I'd say It looks like asking a kid to push a truck uphill.

I don't know what size or make the monitors are, and if the thunderbolt got configured. 

But on paper it can be done.



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Super User

Just as a general statement, if you have two monitors to connect and your USB-C port does not support Thunderbolt, then you want to connect them using a DisplayPort Multi-Stream Transport (MST) Hub device. Your dock has such a hub, but is hampered by needing to also support USB. A USB-C MST Hub device dedicated to exclusively (i.e., no USB) supporting the two monitors will allow two QHD monitors to run at 60Hz. Here are some examples:

  1. For connecting two DisplayPort monitors:
  2. For connecting two HDMI monitor:

Once you move up to that latest equipment with DisplayPort 1.4 support, this problem becomes less of an issue (unless you are also talking 4K or higher resolution monitors!). There are MST Hubs built specifically for this scenario:

  1. For connecting two DisplayPort monitors: 
  2. For connecting two HDMI monitor:

Hope this helps,


P.S. These links are for example only; they are not endorsements for these products.

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Super User

I should also add that these examples are of the higher cost variety. There are definitely cheaper ones around!


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Oh thank you for saying that.

I was trying to find a nice way of saying ;

You will not see QHD display on 2 external monitors. That kind of signal strength cannot be fed through a Thunderbolt.

The premise of 2 4x externals at 60Mhz was misleading.

The thunderbolt was maxed out and the monitors were just sitting there. As soon as you try to do something one of them will shut off.

Just plug the monitors directly into the system.

You might even get by doing it with 16Gigs of ram. 

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