XPS 13 7930 external monitor not connecting

I know you said W10 and drivers are up to date. Did you check for updates through SupportAssist? Also have you ran any diagnostics in SupportAssist or BIOS?

This forum thread may help. Especially the comments by @jphughan  who has expertise with that problem and is very knowledgeable. 

The firmware of the monitor is updated now, and I retried all the ports and turning everything off and on again but still no luck.

Thanks for the reply, I read the thread you linked.
Here the recommondation is the use a USB-C to USB-C cable, and that is what I am already doing.

They have a second recommondation in case that is not an option (which it is on my setup) and that is to use a USB-C to Displayport cable.
I presume this would work, but I would loose the power supply and upstream function with this.

In the support assist everything is up to date and there are no issues in the diagnostics.
In the bios everything is also up to date and also no issues with the diagnostics.

I have not tried to update the firmware of the monitor yet, so I'm trying this now.

@sj86  Can you confirm the system you’re using? There’s no XPS 13 7930. There’s a 9370 and a 7390 though, and there are both regular clamshell and 2-in-1 variants of the latter. This can potentially matter given that you’re dealing with an 4K display, because of those three systems, only the 7390 2-in-1 would be able to run 4K 60 Hz and USB 3.x over a single USB-C cable simultaneously. The others would be limited to either 4K 30 Hz + USB 3.x or 4K 60 Hz + USB 2.0. Just fyi in case that’s important to you.

That said, all of those systems should support video output over a USB-C to USB-C cable out of all of their ports, so if you’ve already confirmed that the cable works properly with another system, and you’ve updated drivers and firmware on the XPS 13 side, and you’ve updated firmware on the display side, then you may have stumbled on one of the tech world’s many annoying cases of interoperability issues that shouldn’t exist but do nonetheless. The first XPS 13 to include USB-C, namely the 9350, has an interop problem that renders it unable to output video over a USB-C to USB-C cable when connected to Dell’s own USB-C displays, even though it works fine with multiple other display brands, and USB-C to DP works fine, and Dell USB-C displays work fine with other systems.

In terms of a workaround, if you want to keep the display, there are USB-C to DP cables and dongles that incorporate a USB-C power input, like this one

@sj86  Apologies, my original post contained a link to the wrong product. I have just edited it to fix that.

It is indeed the XPS 13 7390, the regular clamshell, not the 2-in-1.
I have updated everything on both the laptop and the monitor.

Thanks for the info about the limitations and for the link about the dongle.
This dongle would also allow for the monitor to be used as an upstream hub?

I found some other issues online from people having connection issues with the monitor one other devices, so I'm going to send the monitor back to the shop under warranty and have them have a look at it.

Thank you for the link, will read it this evening.

So I would be better of using the usb-c for power/downstream data and also connecting a different usb-c to displayport cable to the monitor for video/sound?

But the xps also has two usb-c thunderbolt 3 connections, can they run 4K 60 Hz with HDR plus USB 3.x simultaneously? (I mean this given they could actually fix the usb-c connection issue in the shop)

I'm glad to have some new information on the topic!

@sj86  Thunderbolt capabilities only come into play when dealing with actual Thunderbolt hardware, and your LG display appears to be a USB-C display, not a Thunderbolt display.  Thunderbolt displays are relatively rare.  But even if you DID have Thunderbolt, that would give you two full DP 1.2 interfaces plus PCIe.  That would be enough bandwidth to run dual 4K 60 Hz and USB 3.x simultaneously, but even though that's all running over a single cable, from the GPU's standpoint those are two separate interfaces, and I don't think you can combine their bandwidth to drive a single display.  NVIDIA and AMD GPUs support that sort of interface aggregation, and in fact Dell's early 5K display and their 8K display leveraged that capability to run their native resolution and refresh rate over two physical cable connections since a single connection of their eras didn't offer enough bandwidth. But you'd still have the problem that DisplayPort 1.2 as a spec has no formal support for any of the HDR standards anyway.

If you want to learn more about this, I actually wrote an explainer post about the various modes of USB-C and Thunderbolt ports, including their impact on display capabilities, over here. It causes so much confusion that I figured it was worth organizing that information somewhere, so there you go.

@sj86  If you want to use 4K 60 Hz from a non-Thunderbolt display, yes you'd want to run USB data over a separate cable.  If the display itself provided an extra port for that purpose, then you would just have two cables between your PC and the display.  Otherwise you could get a separate USB 3 hub.  But to be clear, there's no sort of "splitter cable" you could use on the display side in order to have two cables from your system converge into a single USB-C port on the display and achieve full functionality.  You can perform that sort of breakout on the system side, i.e. a dongle that plugs into a system USB-C port and gives you separate video and USB ports, but you can't aggregate signals on the peripheral side.

The alternative would be to get 4K 60 Hz display that actually supports Thunderbolt.  Those do exist, and in fact LG makes some.  Those will allow 4K 60 Hz and USB 3.x simultaneously, in fact you could even daisy chain a second 4K 60 Hz Thunderbolt display in that setup and still only have a single cable coming from your system running everything, but they are likely to be more expensive.

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@sj86 wrote:

Hi,

I recently bought an LG 32un880-b monitor.

When I connect my dell laptop to it with the provided usb-c cable the laptop charges but it cannot find the monitor.
I tried all the ports of my laptop and the cable is usb-c to usb-c without any hubs in between and also while charging the laptop with the power adapter.

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Good to see that @jphughan is here helping you (as he is an expert on these kinds of issues) . I just wanted to drop in and mention that the Monitor should never been charging the laptop.

Do whatever you want with other cables, but be sure to connect the supplied Dell (USB-C plugged and proper-wattage) AC-Adapter directly to the laptop. There are very few exceptions to this rule.

And finally, not sure if this is any help, but I did recently test an external monitor on a XPS here:

https://www.dell.com/community/XPS/XPS-15-9520-external-monitor-problem/m-p/8273015/highlight/true#M102290