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m15 R1, thunderbolt docking station and discrete graphic
Hello,
Have 2 questions:
1. Is there a thunderbolt dock which will use Nvidia discrete GPU when using external monitor?
2. Is it possible to charge laptop with thunderbolt port (looks like not per search but wanted to verify)
Greg
jphughan
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September 4th, 2019 16:00
@artisticcheese NVIDIA Optimus is a technology that was developed when dual GPU systems were introduced. Basically, it allows a discrete GPU to be used even when it's not physically connected to any display outputs. Instead, it operates as a "render-only" device that renders the video frames and passes them through to the Intel GPU, which IS connected to the outputs, and then the Intel GPU sends the content to the display. The main reason for this design is battery life, because it means that the discrete GPU can be completely disabled when it isn't needed. If the discrete GPU were directly wired to display outputs, then it would have to stay active whenever a display was attached to those outputs, even if nothing graphics-intensive was going on.
You don't have to worry about whether docking stations support NVIDIA Optimus, because docking stations don't have to support it. You just need a docking station that taps into the "DisplayPort Alt Mode" capability of USB-C/TB3 ports to get video out of the system. That would mean that it's directly connected to a GPU, and even if it's the Intel GPU, the system having Optimus means that the NVIDIA GPU will be able to accelerate content being shown on those displays. The overwhelming majority of USB-C docks -- and I believe ALL Thunderbolt 3 docks -- work this way for video. The only notable exception I'm aware of is the D6000, as I mentioned above, and that's because it's designed to also support being connected to systems over USB-A ports. USB-A ports do not support having native GPU outputs wired to them, so the D6000 had to use an alternative technology to receive video from the system that worked over USB-A. That technology is DisplayLink, which works by transmitting video as regular USB data, but that technology comes with a significant number of drawbacks. I wrote a detailed post about DisplayLink and its drawbacks in this thread, specifically the post marked as the answer, if you're curious. But again you shouldn't have to worry about that.
But as long as you have a dock that uses native GPU outputs, yes performance should be equivalent to what you've got now. The only exception is that as I said above, certain specific technologies won't be available -- although it's possible that those aren't available even under your current setup. It depends on which GPU the HDMI output is wired to. If you want to check, open NVIDIA Control Panel and go to the PhysX Configuration section. That area has a diagram showing which display outputs are wired to which GPU, although it might only show display outputs that actually have a display connected to them at the time. And G-Sync only works over DisplayPort anyway, fyi, so you wouldn't be able to use that in your current setup.
Alienware-Eimy
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September 4th, 2019 13:00
Hi @artisticcheese
1. There are no validated docks for Alienware systems. We do not recommend them due to power consumption.
2. Unfortunately not.
artisticcheese
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September 4th, 2019 13:00
I'm confused what is the point of having thunderbolt port on this computer if main features it can be used for are unusable (that is connecting docking stations) or using it for external monitor.
jphughan
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September 4th, 2019 15:00
@artisticcheese there are other Thunderbolt peripherals, such as eGPUs and external NVMe SSD enclosures. There's also no reason you couldn't attach a display directly to the USB-C/TB3 port. Nothing in the response above ruled that out. That said, even if there aren't any officially recommended docking stations, as long as you keep the system's AC adapter directly connected, you should be able to use a Thunderbolt docking station without worrying about power issues because you won't be relying on the Thunderbolt connection for power -- and the M15's power requirements exceed what can be delivered over USB/TB3. If you search around here, you will find people using Alienware systems with docking stations like the Dell TB16 and even some third-party models.
In terms of your other questions, my understanding is that all current Alienware systems have the USB-C/TB3 port wired to the Intel GPU, which means the dGPU can be used can only be used via NVIDIA Optimus. That is typically fine for most gaming (since the built-in display is wired the exact same way and therefore uses the same setup), but Optimus does prevent you from using certain technologies that require the Intel GPU doesn't support passing through and/or that require the NVIDIA GPU to have direct control of the display output, such as VR, Adaptive V-Sync, G-Sync, stereoscopic 3D, 5K resolution, and possibly others. The thing you absolutely want to avoid is using a dock that relies on DisplayLink technology for video, such as the Dell D6000, since that will not allow the discrete GPU to be used at all. That's due to a Windows limitation. But there are no Thunderbolt docks that use DisplayLink to my knowledge.
I doubt the M15 supports charging at all over USB-C/TB3, although even if it did, the USB Power Delivery spec tops out at 100W. Dell did something proprietary with some of their docks and laptops to stretch that to 130W, but even that wouldn't be enough to run the system optimally.
artisticcheese
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September 4th, 2019 15:00
I currently play Age of Empires 3 via HDMI connection, if I have TB16 connected and also wire HDMI as output will that allow me to experience the same gameplay perfomance as I have currently? I'm not familiar with terms you mentioned but appears based on your response Nvidia will still be used for game rendering?
Also how do I know if docking station supports Nvidia Optimus? For example search for "alienware m15 docking station" first link advertises CalDigit TS3 plus. Does it support it? Or Dell WD15 dock.