Latitude 5510 attaching multiple monitors

@Giagaffney You have a variety of options.

• If your system has Thunderbolt 3, which I think was optional on that model, you can use a Thunderbolt 3 dock like the WD19TB and connect all of those displays to the dock.
• If you only have regular USB-C, with that system you can run dual 1080p displays from a regular USB-C dock like the WD19, and then you can connect the third to the system's built-in HDMI output.
• If you don't care about docking functionality, you can get a triple output MST hub like this one and connect all 3 displays to that.  This will work even on regular USB-C systems since unlike the WD19 dock, this wouldn't be running video and USB 3.x simultaneously, which means it has access to twice as much bandwidth as a WD19 and therefore can run 3x 1080p displays.  (But it still only has access to half the bandwidth that the WD19TB would if your system had TB3.  With that setup you could run triple displays up to QHD/1440p each.)

Thanks for your reply. I do have a Dell docking station K20A001 that I attached all three monitors to but it still won’t detect the third monitor.  Not sure what I’m doing wrong.

@Giagaffney  K20A001 isn't a Dell dock model.  That sounds like a regulatory code.  Can you find the actual model?  It should be something like WD15, WD19, WD19TB, TB16, etc.  But if you're trying to run 3 external displays, then you won't be able to use the built-in display at the same time since the GPU only supports 3 displays max.  So you might have to go to Windows Display Settings and explicitly set the built-in display to Disconnected before you can choose to use the third external display.  If that doesn't resolve it, please provide some more details about exactly what dock outputs you're using and what cables you're using to connect them to which inputs of the displays.  Getting technical assistance requires providing basic technical information so that the people here who are willing to help have something to work with.

Sorry it’s a Dell WD19. I used two hdmi cables and one display port to hdmi cable. I did disable my laptop as a screen. 

I did try plugging the third monitor directly into my laptop and that didn’t work. I will check my laptop to see if it has TB3. I apologize if you didn’t think I followed your directions. Wanted to see if my docking station could handle it before I invest additional dollars. I do find your comments rather off putting. As you may have realized, I’m not very well versed in trying to figure this out. 

@Giagaffney  Also note that I did specifically mention the WD19 as an option in my list above, but with a note that you could only run 2x 1080p displays that way and would therefore have to connect your third display via the system's built-in HDMI output.  The issue about bandwidth that I described above is why I said that.  Did you try that setup?  I gave you 3 options that would work, and you seem to have picked Option #4 and now you're wondering why it's not working.

@Giagaffney  I'm also not clear how you managed to connect all 3 displays to the WD19 using two HDMI cables and a DisplayPort to HDMI cable.  The WD19 only has a single HDMI output, so you couldn't connect two regular HDMI cables to it.  Did you mean two DisplayPort cables?  If so, then I'm wondering about that DisplayPort to HDMI cable, because if you're already using the two DisplayPort outputs, then the only way to connect that DisplayPort to HDMI cable would be to use the HDMI output on the dock and the DisplayPort input of the display.  That will not work.  DP to HDMI cables have to use a DisplayPort output and an HDMI input.  So you might have a cabling problem on top of the bandwidth problem that caused me not to even suggest what you're attempting in the first place.

@Giagaffney  Sorry to hear that you find my comments off-putting.  But when somebody asks for assistance, then I volunteer my time to suggest multiple solutions, and then see that they seem to have just gone their own way instead, hopefully you can understand why that's frustrating.

In any case, if you want to keep the WD19 rather than buying a Thunderbolt dock, assuming your system even has Thunderbolt, then you'll need a regular HDMI cable to connect one of your displays directly to your system -- not an HDMI to DisplayPort cable.  For the remaining two displays that you'll be connecting to the dock, you can use any two of the four video outputs on the dock that you want (except HDMI and USB-C, which can't be used together), but not necessarily any CABLES that you want.  Regular DisplayPort cables will work, as will a regular HDMI cable, as will a DisplayPort to HDMI cable if you use the DisplayPort end for the dock rather than the display.  You could even use a USB-C to DisplayPort or USB-C to HDMI cable.

@Giagaffney  The regular WD19 is not a Thunderbolt dock.  It is a regular USB-C dock, and since the Latitude 5510 only supports DisplayPort 1.2/HBR2 over USB-C, it doesn't have enough bandwidth to run 3x 1080p displays with a regular USB-C dock.  That's why I didn't mention a regular USB-C dock in my list of options, but DID mention the WD19TB Thunderbolt dock if your system has Thunderbolt 3.   A TB3 dock when paired with your system if it supports TB3 would be able to tap into 4x as much video bandwidth as the regular WD19.  But do verify that you have TB3, since otherwise the WD19TB would operate in USB-C backward compatibility mode, in which case it would work just like the WD19 you already have.

Ok I did plug the third monitor directly into the laptop which only has a display port and it didn’t work.  Is that a reason it wouldn’t work?  I do have the TB3 technology, but have read awful reviews. Do you have any opinion on that dock?  

This is the back of my dock and it does have two hdmi and one display port. I also double checked and it is WD19 on the label. 

@Giagaffney  It seems like you're confusing DisplayPort and HDMI.  In the photo of the dock that you attached, the two ports that have cables plugged into them are DisplayPort, and are labeled as such.  The open port between those ports and the USB-C port is HDMI, and is labeled as such.  And the Ports & Slots diagram on the Latitude 5510's product page here shows that the output on the right is an HDMI port.  So, did you try using a regular HDMI cable to connect the HDMI output on your laptop the HDMI input of your third display?  And did you change the input of that display over to HDMI, not DisplayPort?

Clearly I have no idea what I’m doing. Can you just come over and fix it for me lol?  Just kidding. So I did buy the MST triple display that comes tomorrow and saw a diagram exactly which cable to attach where. Thank you for all your help. I now know the difference between a display port and HDMI port.  

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