Thunderbolt 3 ports use DisplayPort for video data, so if G-Sync is possible on your system (and it might not be for a reason I’ll get to below), then it would work even through a dock as long as you used a DisplayPort output on the dock and used a dock that tapped into the native GPU outputs on TB3 rather than handling video through DisplayLINK technology (not to be confused with DisplayPORT) like the Dell D6000. But you didn’t specify the type of dock you’re using.

Adapters that plug into a USB 3.0 port definitely will not work, and in fact you’d get horrible performance for games from those because they use “indirect display” technology like DisplayLink, which they have to because USB ports don’t support native video output. And DisplayLink has some pretty significant drawbacks that are especially prevalent in gaming situations.

You say that MiniDP to MiniDP is an option? Your system has a MiniDP output built in? If so, Mini-DisplayPort is identical to DisplayPort in terms of signaling; it’s just the physical connector that’s different, like USB and Micro USB. So if G-Sync was going to be possible on that system at all, then that would work.

However, even if you had your display connected to your system through a mechanism that used a native GPU DisplayPort output, it’s possible that you still won’t be able to use G-Sync specifically, for reasons I explained in the thread below. It will depend on whether any display outputs on that system are directly controlled by the NVIDIA GPU. And if you can’t use G-Sync at all, then even using a high refresh rate isn’t a great idea, for reasons I also explained in the thread below:

https://www.dell.com/community/XPS/XPS-15-9560-144-hz-monitor/td-p/7353144

@JJacobi92  in addition to the reply I posted above, I would encourage you to try the Mini-DisplayPort output. On some Dell gaming systems, the USB-C/TB3 output is wired to the Intel GPU, but the Mini-DisplayPort output and sometimes the HDMI output are instead wired to the NVIDIA GPU specifically to allow those ports to be used for gaming technologies like G-Sync, VR, and some others. As you found, G-Sync specifically requires DisplayPort, so HDMI won’t work even if that port is wired to the NVIDIA GPU, and the dock might not work if the TB3 port is wired to the Intel GPU, but the Mini-DisplayPort output might meet both requirements and allow you to use G-Sync. Good luck!

@michaelmass  I know it would work with them in the sense that you can send a picture to them, but my understanding is that you wouldn't be able to use the actual G-Sync feature with them.  The Dell D6000 uses DisplayLink (not to be confused with DisplayPORT), and due to a Windows limitation, that means that on systems with both Intel and NVIDIA GPUs active, you can't even use the NVIDIA GPU's graphical acceleration horsepower, because DisplayLink will only allow you to use the primary GPU, which in dual GPU systems will be the Intel GPU.  And G-Sync requires not only that the NVIDIA GPU be used, but that it have direct control of the display output connector.  On most laptops, the NVIDIA GPU doesn't have direct control of any outputs and instead works through NVIDIA Optimus as a render-only device that passes completed video frames to the Intel GPU, which IS directly connected to the display outputs.  But DisplayLink in particular is an "indirect display" technology that involves compressing rendered video and transmitting it as regular USB data.  That's how the D6000 and other DisplayLink-based adapters and docks can support plugging into a system over USB-A, which has no native video output support.  So in that case, NEITHER of the system's GPUs would have direct control of the display output connector.

If you're claiming that the D6000 supports G-Sync displays and that G-Sync can actually be enabled for such displays when connected through the D6000, what is your source for that?

@jphughan The Dell D6000 dock does support G-Sync monitors

Lots of great information in this thread.

For my own clarity.

My laptop does have a Thunderbolt 3.0

I am looking to get a Dell Thunderbolt Dock the WD19TB, the other one I am considering is the CalDigit TS3 Plus.

I am also going to get two Dell S2716D or two P2415Q monitors, which are both G-Sync enabled.

Will I be able to utilize G-Sync on both monitors?  

If I go with the CalDigit dock it only has 1 DisplayPort out but MST should allow me to connect them.  Will G-Sync work with linked Dell monitors?

@Bobberuchi  Where are you finding that the P2415Q supports G-Sync?  I can't find that indicated anywhere, and it seems very unlikely given that the P Series is Dell's "Professional" line and is therefore focused on features that businesses care about, like built-in USB ports, height-adjustable stands, daisy chaining, etc. -- not gaming features like G-Sync.

But assuming you did buy G-Sync displays, your ability to use it will depend on whether the GPU outputs exposed on the USB-C/TB3 port are wired to the Intel GPU or NVIDIA GPU.  If you want to find out, connect any display or TV to that port using something like a USB-C to DP/HDMI adapter or cable, then go to NVIDIA Control Panel > PhysX Configuration. In there you'll find a diagram showing which GPU controls each active display.  If the display/TV you connected shows as being wired to the Intel GPU, you won't be able to use G-Sync regardless of which dock you get.  G-Sync requires that the display be directly controlled by the GPU and that the display be using DisplayPort (or USB-C, which uses DisplayPort for video traffic).  G-Sync does not run over HDMI, so that won't help you even if you find that the HDMI output is wired to the NVIDIA GPU -- which it might be in order to support VR headsets that use HDMI inputs, since VR also requires being wired directly to the NVIDIA GPU.  But if you don't have a port that meets both of those earlier requirements (direct control by NVIDIA GPU and DisplayPort/USB-C), then you can't run G-Sync.

My error I have a lot of models I am researching.  I think I meant to put in the S2417DG not the P2415Q 

I ran the Nvidia control and dxdiag and both indicate the monitor on the TB3 is drawing from the RTX 2070

So would I be able to run G-Sync to dual monitors via a single Display port and carrying over using MST or would I need the Dell Dock that has 2 DisplayPorts. 

It does appear there are no UHD monitors that are G-Sync.  And I may opt for the UHD over the QHD in any event. 

@Bobberuchi I'm not a gamer, so the extent of my experience with G-Sync is helping one person enable it on a desktop that had a direct DisplayPort connection.  But if your USB-C/TB3 port is wired directly to the NVIDIA GPU -- which I wasn't expecting, since even Alienware systems have those ports wired to the Intel GPU, unless that's changed recently -- then yes I would think that you'd be good to go with either of those solutions.  Thunderbolt 3 taps into more display bandwidth than regular DisplayPort MST though, so depending on the resolutions and refresh rates of the displays you want to run, an MST option might not work.

As for UHD vs. QHD, if you're going with 27" I personally would stick with QHD, for both gaming and non-gaming reasons.  The gaming reason is that 4K is roughly twice as many pixels as QHD, so that's a lot of additional load to place on your GPU for gaming, especially a laptop GPU.  Of course you could always game at a lower resolution, but then you're running an LCD below its native resolution, which introduces issues of its own.  And even outside of gaming, I honestly don't understand why 27" 4K even exists.  The pixel density of that setup is high enough that you have to enable Windows display scaling to keep things readable -- and many applications still have problems with scaling -- but not high enough to get that razor sharp text "Retina display" experience.  You need 5K for that at a 27" size.  So 27" 4K to me has always seemed like the worst of both worlds.  Meanwhile, I have a pair of 27" QHD displays that I can use perfectly well at the default 100% scaling setting, and the size and pixel density of that setup means that on each display, when using Word or Acrobat I can display two 8.5x11 pages side-by-side in their entirety (margins and all), in either portrait or landscape orientation (the pages, not the display), at full print size (meaning a zoom setting that causes the displayed page to match a physical sheet of paper held up to the display) and STILL have room left over for the Word/Acrobat user interface above and below.

Thank you for that answer. I had been wondering about trying to get to much out of the GPU.  

I have the same laptop too.

The miniDP is THE displayport with access to the internal GPU. You just need a miniDP to DP male cable or if you have an existing full sized DP cable, you just need the miniDP to DP (female) for connection.

You don't want to use the display port of the TB3 because TB3 port in the laptop is virtually express-wired to the CPU PCIE lanes. I would only use the TB3 port of this laptop for external GPUs using the 40GBPS bandwidth bypassing the internal GPU.