Precision 7530 & Precision 7730 owner's thread

Discussion in 'Dell Latitude, Vostro, and Precision' started by Aaron44126, Jun 27, 2018.

  1. jeremyshaw

    jeremyshaw Big time Idiot

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    yeah, the WD19 (vanilla) uses a Slimport chip that does the USB-C Alt mode conversion. The specific model number doesn't pull up any datasheets.

    A single USB-C connection has 4 high speed pairs. In the vanilla WD19 two pairs are used for DisplayPort, two are used for the USB 3.0 high speed data (one for each direction). DP usually has four high speed lanes, so only running two limits the bandwidth for each connection.

    Since the manual implies DP1.4+DSC support for the WD19DC, I'd expect the setup to be capable of handling 2 4k60 monitors. This would mean at least one of the USB-C ports on the Latitude 7000 series is wired to the Nvidia dGPU*, since the Intel IGP is limited to DP 1.2 (HBR2), and it doesn't have the data rate necessary to support a twin 4k60 + USB3.0 setup, even with two USB-C connections. For the WD19DC, I'd venture one of the cables handles two DP 1.4 (HBR3) lanes and USB3.0. This would be enough to support the dock and one 4k60 SDR monitor. The second cable would have all four DP 1.4 lanes, allowing another two 4k60 SDR monitors. With HDR, the datarate needed for 4k60 4:4:4 HDR exceeds what two DP HBR3 lanes can support, so support may be iffy (without going into details/guesses).

    I do very much like the WD19 so far. Definitely trouble-free in the few days I've been using it. The power button seems to like longer presses (to wake a sleeping machine), but it has been consistent and reliable so far. Almost like an actual port replicator dock, which is the first time I have been able to say that for any of the USB-C/TB3 docks, hubs, and dongles I have.


    *Checking the specs, yes, the dGPU is wired to the USB-C video outputs, yay! DP 1.4 is supported via the USB-C connections, and running at least two, upto three, 4k60 SDR displays is practically guaranteed to work.

    https://www.dell.com/support/manual...15a91f-1cbf-43d0-845b-aec6eb03f40f&lang=en-us
     
    Last edited: Jul 24, 2019
  2. Aaron44126

    Aaron44126 Notebook Prophet

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    I have played with this a little. If you have graphics switching off or the "discrete graphics output mode" on then the USB-C ports will be wired to the dGPU for display output. If you have graphics switching on and "discrete graphics output mode" off then they will be wired to the Intel GPU. Same goes for the other ports on the back (HDMI and mDP).

    However there seems to be some dynamic switching going on. I have two 4K displays plus the internal display (three total) and I have it set up with Optimus so that they all work off of the Intel GPU (for simplicity of setup). A coworker has the same setup but an extra 1080p display connected as well, so four monitors total, and one of his monitors gets routed out via the NVIDIA dGPU, as the Intel GPU only supports three displays. I've confirmed which monitors are hooked up to which GPU with the Device Manager "View -> Devices by connection" tree.

    [Edit]
    XPS15 wouldn't have a BIOS setting to disable graphics switching but I think it still might have the discrete graphics output mode setting? Not sure. Precision 7000 series is more configurable for graphics output.
     
    Last edited: Jul 24, 2019
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  3. jeremyshaw

    jeremyshaw Big time Idiot

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    Yeah, the Intel IGP is limited to 3 active outputs. Thanks for your insight into the display routing w.r.t. 3-4 displays.




    The reason why I bring up the DP1.2, DP 1.4, and USB-C pair/lane allocations is I believe dual 4k60 SDR monitors will not work via the allocations that I think are possible via DP 1.2 on the WD19DC. It should need DP1.4 for that, which will basically require the Nvidia dGPU to drive one or more of the USB-C outputs.

    That being said, the part I mentioned about "(without going into detail/guesses)" was basically a speculation into the ability of the USB-C IC on the dock, USB-C ICs in the laptop, USB-C Alt mode, or DP to allocate DP lanes for 2 monitors across 2 different USB-C connections. Specifically, with DP 1.2, 4k60 requires 12.54Gbps of bandwidth, and DP 1.2 can only serve 17.28Gbps of effective data across its 4 lanes. In the best case setup for the WD19DC hub, there would be 2 + 4 lanes of DP available across the 2 USB-C cables. In DP 1.2, at least three lanes are needed to drive 4k60 SDR 4:4:4. However, I know for DP 1.0, the only possible allocations were 1, 2, & 4 lanes. I do not know if the current components/specs are smart enough to allocate 3+3 lanes across 2+4 available lanes (across 2 cables!). With DP 1.4, however, this becomes a moot point. 2 lanes are all that's needed to support a 4k60 SDR 4:4:4 monitor's bandwidth appetite, and there should be enough lanes/bandwidth for three 4k60 SDR 4:4:4 outputs (indeed, this correlates directly with what the dock's specification claims).

    With HDR and higher frame rates, all of that goes out the window.

    Basically, I am very curious if the Nvidia dGPU is forced on, just to drive your dual monitor setup via USB-C. The curiosity is purely academic (figure of speech). When you get your WD19DC dock, may you please report back on this little bit of information? Thank you very much!
     
  4. Aaron44126

    Aaron44126 Notebook Prophet

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    Yes for sure, I am interested to see as well.
     
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  5. jeremyshaw

    jeremyshaw Big time Idiot

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    You are right, the XPS 15 (7590) does not have this option. I'd guess it's probably due to the lack of a mux.

    After reading a bit more on the WD19DC manual (also the WD19TB manual), there are some stipulations for display configurations (page 18 for the WD19DC manual's table).

    https://topics-cdn.dell.com/pdf/dell-wd19dc-dock_users-guide2_en-us.pdf

    It appears the USB-C DP Alt Mode port shares its display interface with the HDMI port, so it's an either-or situation with those two. So that means only 3 displays can be used at once on the non-TB3 versions of the dock (TB3 version has an extra TB3 port which allows for quad display configurations). I have no clue how MST works into this, but from what I can understand, it won't increase the max number of supported displays.

    DP 1.4 / HBR3 is basically confirmed to be supported, and one of the notes do seem to imply the dGPU is required for such support in current systems.

    I'm pretty happy, as this does seem like Dell has designed this dock to be useful for some time to come.
     
  6. Ionising_Radiation

    Ionising_Radiation ?v = ve*ln(m0/m1)

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    So, I guess I should be posting this here:

    I've got my replacement Precision 7530 coming in tonight (6-10pm UTC+8), and the Quadro RTX 3000 DGFF coming in tomorrow. Anyone wants to guess how much I paid for it?
    225 SGD including 7% GST = 163.50 USD.

    Not even kidding. I triple-confirmed with the sales rep. This is for a mobile GPU, where MXM modules go for typically 2× to 3× the price of equivalent desktop cards. Even the desktop RTX 2060 and 2070 are nearly 2× as expensive. This is like the best trade deal in the history of trade deals, maybe ever.
     
  7. XeonPlanner

    XeonPlanner Notebook Guru

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    Where did you get the card? Did you get it straight from Dell or from other sources?
     
  8. Ionising_Radiation

    Ionising_Radiation ?v = ve*ln(m0/m1)

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    Direct from Dell. Quoted the part number to them, requested a quote and confirmed the payment some hours ago.

    Part numbers are in this comment in the 7540 thread:
     
  9. Aaron44126

    Aaron44126 Notebook Prophet

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    That price is nuts. Nuts. You should start a business selling them on eBay. :p
    Guess we'll know if the upgrade works soon. Usually we have to wait for next-gen cards to appear on eBay (several months after the new systems release).
    Get ready to have to start modding the NVIDIA driver INF file every time you want to upgrade the driver.......
     
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  10. Ionising_Radiation

    Ionising_Radiation ?v = ve*ln(m0/m1)

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    Indeed!

    I hope not. We'll see tomorrow, I suppose, after I finish my data structures and algos finals in the afternoon. I suppose everyone here will have to wait maybe 15 more hours...
     
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