Mobile GPU output through Thunderbolt?

[AtomAlchemist]

So like many of us I now work remotely and have a work laptop and a personal computer. I switch between them with a DisplayPort x2 and HDMI x1 KVM switch.

 

 

My work laptop is a Dell Precision 5560 with a NVIDIA T1200 GPU and a Thunderbolt docking station with 2 DisplayPort and 1 HDMI port (perfect for my kvm setup)

 

The thunderbolt dock  uses the intel integrated graphics instead of the the NVIDIA GPU. Is there a way to switch this? I've got fairly restricted access, and NVIDIA Control Panel is not installed. If I go into the call with the answer I might be able to get a help desk tech to make the necessary changes under admin.

 

Also is it safe to assume that refresh rates are limited by thunderbolt bandwidth and not the gpu being used? and would driving one display off of an adapter on the 2nd thunderbolt port have any additional bandwith?

 

Thanks! 

[Bombastinator]

Intel machines are supposed to auto switch to a discrete gpu when the load gets high enough.  You say it’s not doing that?

[AtomAlchemist]

3 hours ago, Bombastinator said:

Intel machines are supposed to auto switch to a discrete gpu when the load gets high enough.  You say it’s not doing that?

 

If it's supposed to dynamically swap maybe it's working as intended... I'm not sure how I can tell if it's switches, I guess I could leave display options up on a screen and see.

[Bombastinator]

1 hour ago, AtomAlchemist said:

 

If it's supposed to dynamically swap maybe it's working as intended... I'm not sure how I can tell if it's switches, I guess I could leave display options up on a screen and see.

Generally fans will ramp up and power draw will increase.  The DGPU often draws more power than the entire cpu. It 

[roman.i]

Hey, this question doesn't have a good complete answer on the internet. I'll "revive" the thread so other will have a complete picture of what happening when the video is sent over Thunderbolt. Thunderbolt is a proprietary of Intel. It usually comes built-in for Intel's integrated graphic chips, think Intel UHD, Intel Xe, etc.

Video output of on-board Thunderbolt port from a discrete graphic is impossible probably on all of mainstream motherboards. On desktop PC this requires a motherboard with Thunderbolt header and a Thunderbolt extension card. This card will be connected via DP cabled to the graphic card, and output a Thunderbolt video.

Now, on laptops and mini pc this extension doesn't come by default, probably doesn't exist at all.

So as a result, the Thunderbolt on those devices is hard-bound to the Integrated graphics only.

This is the case even on Intel's Nucs with discrete graphics.

https://www.intel.com/content/www/us/en/support/articles/000058977/intel-nuc.html

[Bombastinator]

1 minute ago, roman.i said:

Hey, this question doesn't have a good complete answer on the internet. I'll "revive" the thread so other will have a complete picture of what happening when the video is sent over Thunderbolt. Thunderbolt is a proprietary of Intel. It usually comes built-in for Intel's integrated graphic chips, think Intel UHD, Intel Xe, etc.

Video output of on-board Thunderbolt port from a discrete graphic is impossible probably on all of mainstream motherboards. On desktop PC this requires a motherboard with Thunderbolt header and a Thunderbolt extension card. This card will be connected via DP cabled to the graphic card, and output a Thunderbolt video.

Now, on laptops and mini pc this extension doesn't come by default, probably doesn't exist at all.

So as a result, the Thunderbolt on those devices is hard-bound to the Integrated graphics only.

This is the case even on Intel's Nucs with discrete graphics.

https://www.intel.com/content/www/us/en/support/articles/000058977/intel-nuc.html

Sort of.  Intel developed it but then joined the USB consortium and then left with the name “thunderbolt”. That’s why there is thunderbolt4 and USB4 but they’re both so similar functionally.  My understanding is thunderbolt4 has a tighter hardware spec so it’s considered superior.  There was a new version of USB4 put out though which had an even higher speed though so I don’t know if that is still true.  My understanding is Intel didn’t think the USB consortium could even make USB4 work at all though with their looser requirements.  There doesn’t seem to be a lot of it around.

[AtomAlchemist]

On 11/19/2022 at 6:44 AM, roman.i said:

Hey, this question doesn't have a good complete answer on the internet. I'll "revive" the thread so other will have a complete picture of what happening when the video is sent over Thunderbolt. Thunderbolt is a proprietary of Intel. It usually comes built-in for Intel's integrated graphic chips, think Intel UHD, Intel Xe, etc.

Video output of on-board Thunderbolt port from a discrete graphic is impossible probably on all of mainstream motherboards. On desktop PC this requires a motherboard with Thunderbolt header and a Thunderbolt extension card. This card will be connected via DP cabled to the graphic card, and output a Thunderbolt video.

Now, on laptops and mini pc this extension doesn't come by default, probably doesn't exist at all.

So as a result, the Thunderbolt on those devices is hard-bound to the Integrated graphics only.

This is the case even on Intel's Nucs with discrete graphics.

https://www.intel.com/content/www/us/en/support/articles/000058977/intel-nuc.html

Thank you for sharing this. I should have circled back on my thread but this is the conclusion I came to. Luckily there's not a strong need to use the discrete gpu on my work laptop, and I didn't pay for it so it's not like I'm kicking myself for leaving that functionality unused, but this seems like a step backwards for laptops, especially since they've moved away from other docking solutions that had this functionality in favor of USB-C or Thunderbolt docks. 

[Qyygle]

Considering the laptop probably uses Optimus however, I'm not sure that description marked as answer is necessarily true.

The NUC doesn't have an optimus switch, it only has integrated graphics, to connect a seperate GPU to the NUC, you already are using a thunderbolt eGPU dock. The NUC is probably not setup to route from an eGPU to the NUC to another thunderbolt dock.

However on a more traditional laptop with dgpu and optimus, the dGPU is commonly already routed through the integrated graphics. Laptop reviewers often talk about gaming laptops having a 'mux' switch, where they can switch off the integrated graphics fully and route direct through the discrete gpu. In your case, you're actually looking for optimus to be on, so the dGPU can route through the integrated graphics to the thunderbolt dock monitors. For most laptops, this should work.

 

I think if you go into Windows display settings, 10 and 11 have moved the original Nvidia Control Center settings into generic windows settings.

[Bombastinator]

On 11/19/2022 at 5:44 AM, roman.i said:

Hey, this question doesn't have a good complete answer on the internet. I'll "revive" the thread so other will have a complete picture of what happening when the video is sent over Thunderbolt. Thunderbolt is a proprietary of Intel. It usually comes built-in for Intel's integrated graphic chips, think Intel UHD, Intel Xe, etc.

Video output of on-board Thunderbolt port from a discrete graphic is impossible probably on all of mainstream motherboards. On desktop PC this requires a motherboard with Thunderbolt header and a Thunderbolt extension card. This card will be connected via DP cabled to the graphic card, and output a Thunderbolt video.

Now, on laptops and mini pc this extension doesn't come by default, probably doesn't exist at all.

So as a result, the Thunderbolt on those devices is hard-bound to the Integrated graphics only.

This is the case even on Intel's Nucs with discrete graphics.

https://www.intel.com/content/www/us/en/support/articles/000058977/intel-nuc.html

Not sure what was meant there.  It is property of intel and it used to also be proprietary.  It got open sourced a while back though.  So property, but no longer proprietary.  There’s an LTT video about thunderbolt 3 and usb4, which I took to mean that usb4 COULD be actually a bit better than thunderbolt3, but could be just more or less usb3.1, which means in some cases it will be.  So basically USB4 can’t be trusted to be worth anything as it may actually be a step backward rather than forward, and reviews will be needed to see if the label is actually useful or not on a given device.  Not 100% I got that right but it’s how it seemed to me.USB4 is apparently thunderbolt3 so infected by marketer douchbagginess that it may actually be worse.  “Dawid does tech stuff” will no doubt have a term for such things related to some venereal disease or other, which I think is appropriate in this instance

Edited December 1, 2022 by Bombastinator