3 Monitors on Latitude 5480 & K17A Docking Station

Hi LVHNJohn,

Thanks for posting.

It appears what you have is a WD15.  Please contact Dell Tech Support for assistance.

The laptop and its GPU can indeed handle 3 displays, but due to bandwidth limits of regular USB-C when it's being used for both display and USB traffic simultaneously (as is the case with a dock), the WD15 only receives enough bandwidth to support 2 displays up to 1080p. That is indicated on the WD15's product page, the manual available on support.dell.com site.

If you want 3 displays, the last page of the manual does list that as a possibility, but only at pretty low resolutions.  Other than that, you can get 3 displays either by using the laptop's built-in panel with your 2 external displays, or if your 5480 has Thunderbolt 3 (optional on that model), you could get the TB16 dock, which will allow 3 external displays up to 1080p or 2 displays up to 4K because Thunderbolt allows 4x as much display bandwidth as a USB-C connection that is carrying display and USB traffic simultaneously.  In fact it has enough bandwidth to handle 4 1080p displays, but that's not officially listed as supported, and even if it works it might require additional hardware (such as a DisplayPort MST hub connected to the dock) and of course a system whose GPU supports 4 displays.

I wrote a long thread about USB-C and Thunderbolt configurations and bandwidth in general here if you're interested: http://en.community.dell.com/support-forums/laptop/f/3518/t/20017807

I have a P4317Q and should be receiving a 5480 soon, which dock (if any) would be suggested to support 3 displays within the P4317Q?  i'm ok with 1920 x 1280 resolution.  

3x 1080p with a docking station would require the TB16 dock (you can use either the 180W or 240W AC adapter version with that system), but that dock in turn requires that your laptop support Thunderbolt 3.  That is OPTIONAL on the 5480, not standard, so make sure the one you're getting includes that option. The standard configuration is USB-C with DisplayPort Alt Mode, but that would not provide enough bandwidth when used in a DOCKING setup, such as with the WD15.  You'd only get 2x 1080p in a docking setup.  HOWEVER, even if you're stuck with a regular USB-C port, you CAN get enough bandwidth for 3x 1080p if you use that port SOLELY for display output, i.e. not having it also carry USB traffic as it would with a dock.  The way you would achieve this would be USB-C to DisplayPort (female) dongle into which you would connect a DisplayPort MST hub.  That would get you 2-4 outputs (depending on the hub) into which you would connect your display cables.  Note that some MST hubs allow using any old DisplayPort to HDMI/DVI adapters on their outputs if needed because they natively support Dual Mode DisplayPort, whereas other hubs do not and instead require less common and more expensive ACTIVE adapters to convert to HDMI/DVI, assuming that's even a concern for you.

CORRECTION: I may be wrong that the 5480 can use the lower-wattage AC adapter option on the TB16.  Since it uses H Series CPUs, it might require the TB16 version with the 240W adapter.  Unfortunately, the TB16 FAQ page doesn't specifically mention the 5480's requirements, only the Latitude 15 series and the 7480.

However, since the TB16 cost is typically the same regardless of AC adapter and the only difference is the physical size of the AC adapter, which most people stick under a desk on the floor anyway, I would play it safe and get the larger adapter.  Some systems even if they only require the lower-wattage option will charge faster when more wattage is available. Apologies for the confusion.

I also have a question on a similar setup.  I have a new 5280 and have both the TB15 and TB16.  I want to run dual 20" screens, one DVI to display port, one vga, and then a hdmi to my 28" LCD vizio tv.  My old E7440 had no issue with it's advanced port replicator.  I can't get this setup to work though.  I am getting nothing on all three screens using the TB16.  I can get the two 20" to work through only the TB15.  Is this just not a viable solution?

First off, why do you even still have a TB15?  Dell recalled all of those due to massive problems and gave everyone who had one a free replacement to a TB16.  I imagine you can still get that now, and using a TB15 may itself be the source of all of your problems. Everything I'm going to mention below pertains to the TB16.

Second, it would help a lot if you specified the resolutions of the displays you're trying to run.  Display size is irrelevant.

According to the "Display Resolution Table" in the TB16 manual, available from support.dell.com, triple displays are supported up to 4K @ 30 Hz, which would also allow 1080p @ 60 Hz since that uses half the bandwidth of 4K @ 30 Hz.  In fact even quad display is supported up to that resolution, with just a note that VGA is limited to 1080p in this configuration.

So yes, your setup should be attainable.  The curve ball in your case may be using the DisplayPort to DVI adapter and VGA simultaneously.  I'm not sure how many outputs the dock can send that are NOT native DisplayPort.  The display traffic the dock receives from the system is 100% DisplayPort, and converting that signal to HDMI,  DVI, or VGA requires that the dock perform that conversion.  The TB16 does support that, but it may not support more than one at a time; I'm not sure, and I don't see anything about that in the manual.  If either of your displays support native DisplayPort, you might want to try that.  If not, then you should at least get off of VGA.  That's the only analog signal of the bunch, and as such it looks noticeably worse than DisplayPort, HDMI, or DVI; the extra adapter will be worth the improvement.  As a last resort, there are so-called "active" adapters that perform a DisplayPort to HDMI/DVI conversion within the adapter itself, which would then remove the requirement for the dock to do this.  They're less common and a bit more expensive, and as I said, I'm not even sure that's the problem, but it may be worth ordering one just to test with, seeing as you can always return it if it doesn't help.

Ok.  The 2 x20" displays are both running 1680x1050 one via vga and one via DVI to a mini-display port dongle that came with my laptop.  I'm ok with that.  They are Dell 2007 WFP Ultrasharps, so only VGA and DVI options.  The LCD is only getting 1024x768 via hdmi and these are all running through a WD15 not a TB15.  I have the TB16 as well but it won't even light up a single connection...so not sure what's up with it.  Just trying to get one dock to work with the best picture possible on 3 screens.  Right now the LCD has large border bars around the picture.  So I have HDMI, Mini-DP, DP, VGA on the TB16.  Which connections should I use for this setup to yield the best resolutions.  Is there any updates I need to run on my laptop and/or the TB16 to get it functional?  It powers up and will connect everything but the screens.

The WD15 only uses USB-C, not Thunderbolt, and since that USB-C connector is ALSO being used to carry USB traffic for the dock's USB ports, the end result is that it has half the bandwidth of a DisplayPort 1.2 output available for display data.  That is enough bandwidth to support 2x 1080p @ 60 Hz.  If you're running two displays at only 1680x1050, you'll have some bandwidth left over for a third display, but it might only be enough to run 1024x768.  I believe the MiniDP and HDMI outputs get bandwidth priority over VGA.  You can read more about supported resolution and display combinations in the WD15 manual, available at support.dell.com.

The TB16 has enough bandwidth for two full DisplayPort 1.2 outputs, or 4x the bandwidth of the WD15.  On that side, is it just the displays that don't work, or are the USB ports, audio output, and Ethernet connector also non-functional?  Make sure you've installed the latest versions of all of the following components, in this order:

- System BIOS

- Thunderbolt software

- Thunderbolt firmware

- ASMedia USB Host Controller driver

- Realtek USB Ethernet driver

- Realtek USB Audio driver

If you still can't see anything, open the Thunderbolt Software on your PC while the dock is connected.  Do you see "Dell Thunderbolt Dock" and "Dell Thunderbolt Cable" listed in the Attached Devices window?  If not, check your BIOS and make sure Thunderbolt is enabled.

I don't see thunderbolt software on my pc anywhere.  I updated bios and all drivers as listed in the tech doc I found on dell.com.  Still nothing.  I looke din bios and all the thunderbolt menu options are greyed out...does this laptop not have that capability?  is it optional?

Thunderbolt is optional on the 5480, and if the Thunderbolt options in the BIOS are completely grayed out, it means your unit doesn’t have it. Lack of a Thunderbolt logo next to the USB-C connector on the laptop itself would be another indicator. In that case you can’t use a Thunderbolt dock at all since they are not backward compatible with regular USB-C even at a reduced functional level.

I have this exact same situation, with the Latitude 5480 and the WD15 dock.  

The answer is actually really easy.  You connect two monitors to the dock, and the third via the HDMI cable to the HDMI port on the back of the 5480.  It requires you to plug in and pull out two cables when you dock/undock, instead of just the USB C cable, but I am doing it right now and it works.

^ That is indeed a viable workaround, since in that case the third display's data isn't being sent over USB-C, which wouldn't have enough bandwidth for it.