32:9 resolution on Precision 3550 with WD19

@cdl0885  To expand on my post above a bit, the Intel GPU in your system does support 5120x1440.  It supports up to 3 total displays, each of which can be up to 4K 60 Hz, and 4K is slightly more total pixels than 5120x1440.  Your issue is a bandwidth issue because the GPU only supports DisplayPort 1.2 over USB-C.  If it supported DisplayPort 1.4 over USB-C, you'd be fine with the regular WD19, but since it doesn't, you need the WD19TB.  You might also need a registry patch to enable 5K support.  That's provided here, but that patch also notes that it's for the HD 630, so you might not be needed on the 620.  But in case you need it even after fixing your hardware limitation issue, there it is.

@cdl0885  The NVIDIA GPU in that system is not directly connected to any display outputs. It operates as a render-only device through NVIDIA Optimus. This is the most common design for dual GPU laptops. The Precision 7000 Series have a BIOS option allowing you to change this, and the new 5750 does when you have an RTX GPU installed, but that’s about it within the Precision line.

As for the WD19, you can’t run that resolution through that dock from that system. Your system only supports DisplayPort 1.2 over USB-C, and because the dock is setting up the USB-C link to support both video and USB 3.x, you only have half of a DP 1.2 interface worth of video bandwidth, which isn’t enough to run 5120x1440. The WD19 when paired with that type of system can only handle a single display up to 2560x1600 or dual displays up to 1920x1200 each. This is outlined in the WD19 User Guide on support.dell.com. But your system supports Thunderbolt 3, which means if you got the WD19TB, you’d be fine. That dock when paired with your system can handle dual displays up to 4K 60 Hz each or triple displays up to 2560x1440 each because it can tap into 4x more display bandwidth than the WD19.

@jphughan 

Wow, I'm really surprised by that limitation with the DGPU, but thanks for the information.

Since it looks like my dock is the limitation I tried to use the laptops built in HDMI out and bypass the dock. This allows me to select resolutions up to 4k but it still will not allow any 32:9 options (either 5120x1440 or 3840x1080). I've tried setting a custom resolution in the Intel Graphics Command center, but trying both resolutions it says Mode Not Supported. I don't want to spend on another dock until I am certain I will be able to get this working.

EDIT: it looks like the HDMI port on this laptop is only version 1.4 compatible? so max at 4k30? Indeed if I chose 30p refresh rate in Graphics Command Center it will allow me to enter my desired resolutions as custom resolutions. So It looks like the TB dock is the only way to get 60p or 120p working?

Thanks

@cdl0885  Regarding the dGPU setup, that's been the most common dual GPU setup in laptops for several years, especially in Dell's products.  Even the Precision 5000 Series models are set up that way, except for the brand new 5750, and then only when you get the RTX GPU.  See my post marked as the answer in this thread if you want to learn more about the various dual GPU implementation options and the pros and cons of each.

Regarding HDMI, the Precision 3550's HDMI output only supports HDMI 1.4, which only has enough bandwidth to run 4K at 30 Hz, not the standard 60 Hz.  So if your custom resolution attempted 5120x1440 at 60 Hz, that definitely wouldn't have worked over HDMI.  You'd need HDMI 2.0 to run that display properly over HDMI.

Not sure what else I can tell you in terms of reassurances.  You could Google "U4919DW WD19TB site:Dell.com" to see forum posts from people talking about running that display through that dock just fine even on systems that have the Intel GPU controlling the display outputs, which again is by far the most common setup especially among Dell's laptops.  And/or I could tell you that I've personally helped people run a U4919DW through a WD19TB even from an older XPS 13 model, which ONLY has an Intel GPU.  If that's not enough and you're willing to spend a little money before spending a lot of money, you can get a USB-C to DisplayPort cable to plug that display straight into your system's USB-C port and get it working.  That will work because in that setup, the USB-C interface won't be set up to support USB 3.x as well like it is with the WD19, and therefore you'll have twice as much video bandwidth available as you do when using the WD19.  But then you'll probably still want the dock anyway and then you'll have no use for that USB-C to DP cable.  Of course you could return the cable at that point, but that would also be true of the dock if you bought it and it didn't work, and yet that option doesn't seem to be enough of a safety net for you.  But good luck with your research and decision whatever you end up doing.