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salemf
1 Copper

m15 R2, Thunderbolt, external display

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Hello!

I just purchased an Alienware m15 R2 and also the Alienware 34 inch screen. I was wondering if i can connect the screen to a dock , the dock to the laptop via thunderbolt 3 and utilize the Nvidia Graphics card or is the intel internal graphics only supported via thunderbolt?

Reason i ask is my wife has a work dell laptop that she needs to connect to the screen also so rather than disconnecting the mouse, keyboard, Ethernet etc every time at the end of the day and connecting my alienware laptop i was thinking of buying a dock so it's one cable only.

What is the easiest solution here?

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jphughan
5 Osmium

Re: m15 R2, Thunderbolt, external display

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Thanks for the kind words! 🙂 Dell Rockstars are just community volunteers, but I like helping people especially on technical stuff like this.

Anyway, somehow I missed those tables before, but yes it absolutely looks like the MiniDP and HDMI ports are controlled by the NVIDIA GPU. In that case I would really recommend that you connect your display via one of those ports. MiniDP would be best, using a MiniDP to DP cable if needed, since that would allow you to run G-Sync. As for the docking station, at that point if you won’t be using it for video or power with that system, a docking station doesn’t seem like a great value. I would recommend that you consider just getting a USB 3.0 hub and plugging all of your other peripherals into that. Then you can just connect your display, AC adapter, and USB hub to get up and running. If you actually need to use Ethernet or the headphone jack (rather than having a USB headset), then I guess those would be more cables that you’d be able to avoid connecting directly if you had a docking station, but a docking station seems unreasonably expensive if you won’t be using it for power or video and instead just need it for USB, maybe Ethernet, and maybe a headphone/speaker jack. Anyhow, good luck and enjoy your system!

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jphughan
5 Osmium

Re: m15 R2, Thunderbolt, external display

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@salemf  the answer might be more complicated than you were expecting, because it depends on what exactly you mean by "utilizing" the NVIDIA GPU, but I'll try to lay it all out intelligibly and (reasonably) briefly.

The type of dock you do NOT want are the ones that use DisplayLink technology (not to be confused with DisplayPort, which is a totally different thing).  The Dell Dxxxx docks like the D6000 are like this.  They are absolutely terrible for gaming for a variety of reasons that I've written about elsewhere, and one reason among several others is that due to a limitation in Windows, displays connected via DisplayLink technology can only use the primary GPU, which in an Intel+NVIDIA dual GPU system will usually be the Intel GPU.  In that case, the NVIDIA GPU will not be able to do anything at all for content on DisplayLink-attached displays.

The other and more common type of dock are the ones that tap into the actual GPU outputs wired to USB-C/TB3 ports, such as the Dell WD19TB.  (Note: The WD19TB will not be able to charge this system because its power requirements are too high, so plan to keep the system's AC adapter connected as well.)  When you use this type of "native GPU output" dock, then even if the USB-C/TB3 port's GPU output is directly wired to the Intel GPU, you will still be able to tap into the NVIDIA GPU's performance when needed thanks to a technology called NVIDIA Optimus.  This is how the overwhelming majority of laptops work, including for their built-in display.  Basically, the Intel GPU has direct control of the display output and is always active, but when additional performance is needed, the NVIDIA GPU starts up as a "render-only" device to do all the work, and then sends completed video frames to the Intel GPU to be passed through to the attached display(s).

The restriction with Optimus is that certain technologies don't work through it, either because the Intel GPU doesn't support passing them through and/or they require an NVIDIA GPU to have direct control of the display outputs.  Such technologies include G-Sync, Adaptive V-Sync, VR, stereoscopic 3D, and 5K resolution (except the new Intel Gen 11 GPUs, which support 5K, but they're currently only found in the new "Ice Lake" CPUs that aren't used in the M15 R2).  The only way to use those capabilities would be to connect your display to an output that is directly wired to the NVIDIA GPU, but most laptops have all display outputs wired to the Intel GPU.  Some laptops, probably including the M15 R2, have at least one output wired to the NVIDIA GPU specifically to allow them to support capabilities like I mentioned, but every Dell system I've seen thus far has had its USB-C/TB3 output wired to the Intel GPU.  The only exception is the more recent Precision 7000 Series models, which have a BIOS option that allows you to choose which GPU controls the display outputs, which they can offer thanks to a more complex and expensive motherboard design.

If you want to verify how your display outputs are wired, connect a display to the various outputs on the system and open NVIDIA Control Panel, then go to the PhysX Configuration section.  In there you'll find a graphic showing which GPU has direct control of each active display output.  My guess is that you'll find that the Intel GPU controls the USB-C/TB3 port while the NVIDIA GPU controls the Mini-DisplayPort output (for DP 1.4 support and DP-based VR headset support) and the HDMI output (for HDMI-based VR headset support).  But that is just a guess.

So what does this all mean?  If you don't care about the "special" technologies I mentioned above that don't work through Optimus and instead just want the benefit of NVIDIA GPU performance, then get a WD19TB and connect your display to that, and you'll be fine.  If you DO care about those special technologies, then if you can ALSO confirm that the USB-C/TB3 port is wired to the NVIDIA GPU, you will still be fine using the dock.  But if you care about those features and the USB-C/TB3 port is wired to the Intel GPU, then you'll have to connect your display to one of the other display outputs built into the system that you confirm is wired directly to the NVIDIA GPU.  (Note: G-Sync only works over a connector that carries DisplayPort signalling, which means DisplayPort, Mini-DisplayPort, or USB-C/TB3.  It will NOT work over HDMI even if that port is wired to the NVIDIA GPU.)

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salemf
1 Copper

Re: m15 R2, Thunderbolt, external display

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Thankyou @jphughan for the prompt and very informative reply!

So checking the Alienware m15 R2 specification manual i can see the following:

 

salemf_0-1577512312887.png

That would suggest what you are saying? that the Nvidia GPU is only wired to the display port and the HDMI?

Therefor if i connect via the thunderbolt port i would still utilize the Nvidia GPU but the G-SYNC module in the monitor and the laptop wouldn't be able to be used?

One last question, if i used the WD19TB dock, would i still be able to drive 3440 x 1440 @ 100hz? Or would the bandwith be limited to 60hz?

Also would this mean i would need one AC adapter for the dock and also one AC adapter for my Alienware laptop?

 

Thank you once again

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jphughan
5 Osmium

Re: m15 R2, Thunderbolt, external display

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@salemfhappy to help! Unfortunately at the moment I can't see what portion of the Setup and Specifications document you're referring to because screenshots are initially only visible to the person who uploaded them and to Dell moderators until they get approved for general viewing.  But looking at the entire document from support.dell.com myself, I'm not seeing any specific language about which GPU each of those outputs is wired to.  Again, if you have the right cables to connect a display/TV to each of those ports, looking at NVIDIA Control Panel would be the most reliable indicator.

But regardless of how the various display outputs are wired, as long as you use a "native GPU" dock like the WD19TB, you will AT LEAST be able to use the NVIDIA GPU for its general performance benefit.  The only question is whether you would also be able to use G-Sync.

As far as 3440x1440 @ 100 Hz goes, the dock would have enough display bandwidth to run that setup, and even the Intel GPU supports up to 4K, which is more total pixels than 3440x1440.  I've also read from other users that the Intel GPU does support 100 Hz.  So all of the indications are that even if the Intel GPU controlled the USB-C/TB3 output, it would run that setup.  However, if you CAN'T use G-Sync or Adaptive V-Sync when connected that way (because the Intel GPU controls USB-C/TB3), then you might want to rethink using a high refresh rate, or preferably connect the display in a way that will allow G-Sync.  The reason is that when G-Sync and Adaptive V-Sync aren't available, the only options are V-Sync Off or V-Sync On.  When it's off, you can get frame tearing, which is what V-Sync is meant to fix.  But if V-Sync is on, then your GPU needs to be able to reliably sustain a frame rate at least equal to the display's refresh rate, which in this case would mean 100 fps, because if the GPU's frame rate output drops below the display's refresh rate, then V-Sync will cause judder/stutter.  Even with a new laptop like an M15 R2, achieving a stable 100 fps in modern games would be a tall order unless maybe you were willing to crank detail settings down.  This dilemma incidentally is exactly why G-Sync exists.  It allows you to avoid frame tearing AND judder by allowing the display's refresh rate to keep adjusting dynamically based on the frame rate the GPU can deliver at any given time -- but that requires the display to support that technology AND for the NVIDIA GPU to have direct control of the display output.  So again, if the Intel GPU controls the USB-C/TB3 output, I would recommend either sticking with 60 Hz since you'll be able to sustain 60 fps more reliably, or else connect the display to the system's Mini-DisplayPort output to use G-Sync instead, assuming that output is in fact controlled by the NVIDIA GPU (and the display you bought supports G-Sync).

But if you do use a WD19TB, yes you'd need to plug in its 180W AC adapter even if you weren't using it to charge your system.  Its 180W adapter would be huge overkill in that situation, but the dock still needs some power to run its internal electronics and provide power to any USB peripherals you might attach, and it will not try to draw that from the attached system, so it needs external power.  And you'd still need to keep your system's AC adapter connected because that system doesn't support drawing power over USB-C since it requires way more power than the USB Power Delivery spec currently allows.

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salemf
1 Copper

Re: m15 R2, Thunderbolt, external display

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You really are a rockstar! thank you for your information and support! i hope dell pay you!!!!

I can't look at the NVIDIA Panel just yet as the laptop still hasn't arrived and im trying to determine which dock to buy!

The screenshot out of the specifications manual (Alienware m15 R2 page 16) is under Video in Table 17 and 18:

https://topics-cdn.dell.com/pdf/alienware-m15-r2-laptop_users-guide_en-us.pdf

Is this what we are looking for?

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jphughan
5 Osmium

Re: m15 R2, Thunderbolt, external display

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Thanks for the kind words! 🙂 Dell Rockstars are just community volunteers, but I like helping people especially on technical stuff like this.

Anyway, somehow I missed those tables before, but yes it absolutely looks like the MiniDP and HDMI ports are controlled by the NVIDIA GPU. In that case I would really recommend that you connect your display via one of those ports. MiniDP would be best, using a MiniDP to DP cable if needed, since that would allow you to run G-Sync. As for the docking station, at that point if you won’t be using it for video or power with that system, a docking station doesn’t seem like a great value. I would recommend that you consider just getting a USB 3.0 hub and plugging all of your other peripherals into that. Then you can just connect your display, AC adapter, and USB hub to get up and running. If you actually need to use Ethernet or the headphone jack (rather than having a USB headset), then I guess those would be more cables that you’d be able to avoid connecting directly if you had a docking station, but a docking station seems unreasonably expensive if you won’t be using it for power or video and instead just need it for USB, maybe Ethernet, and maybe a headphone/speaker jack. Anyhow, good luck and enjoy your system!

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