U4919DW, connecting two computers, how many cables do I need?

@Johannes SL  If you only need USB devices plugged into the display to be available to one of the source PCs you'll be using, then you can use only one USB cable.  If you want to plug peripherals into the display's USB ports and be able to switch which PC they get used with, such as a keyboard and mouse, then you'll need an upstream USB connection from the display to each source PC.  If one of your source systems supports USB-C and provides video output from that port (which is an optional capability of USB-C), then you could use a USB-C cable to connect that system to the display, and that single cable will carry video, USB data, and power if it's a laptop that wants to draw power from the display.

Hi, 

Thank you!

I do need the USB devices to be available for both computers.

So, if one of my computers runs on USB-C I only need one upstream 3.0 cable?

Sounds good.

Thanks for the help and have a nice day.

Best regards,

Johannes

Also - is this the correct kind of cable? I seem to have missed the one that was delivered with the screen.

@Johannes SL  I just saw that I forgot to mention that the U4919DW only supports USB 2.0 over its USB-C port. This has to do with how USB-C works, how much bandwidth the display’s 5120x1440 60 Hz resolution requires, and the fact that it only supports DP 1.2 over USB-C. If you specifically need USB 3.0 to both PCs, run a separate USB 3.0 cable like the one you linked alongside the USB-C cable in order to have a USB 3.0 data path available. And then of course you’ll need 2 total USB 3.0 cables.

@Johannes SL  Yes, that is the correct type of cable. Good luck!

Hi there, jphugan,

Not sure if I follow you...

I just got back from the store with 1 x USB A-B 3.0 (upstream cable) which now runs from my Dell monitor to my main computer. I have now successfully connected my two USB peripherals for my keyboard/mouse. This runs well.

Finally, I have one USB-C cable which was now intended to plug into my other computer. I have not yet tested this.

Are you saying I need one USB 3.0 for this computer, too? 

Best,

Johannes

@Johannes SL  If you'll be connecting the other PC via the USB-C input and you're ok with having your USB data speeds to that PC limited to USB 2.0, then you can use only the USB-C cable. If on the other hand you want USB 3.x data speeds available to that PC, you will need to use a USB-C cable (or another video input) and a separate USB 3.0 connection using a second USB 3.0 cable.  The U4919DW only supports USB 2.0 data speeds over USB-C.  This has to do with how USB-C works (at least until USB4 arrives), the amount of bandwidth required to run 5120x1440 at 60 Hz, and the fact that the display only seems to support DisplayPort HBR2 bandwidth rates rather than DisplayPort HBR3 bandwidth rates.  The latter would have allowed it to run 5120x1440 60 Hz and USB 3.x over a single USB-C connection simultaneously -- if your system also did -- but the display doesn't seem to have that support.  If you're really curious, I wrote an explainer post about the various operating modes of USB-C and Thunderbolt 3, with special attention paid to their impact on possible display setups, over here.

Hi again, jphughan,

This is getting a bit too technical for me. LOL.  

Why would I need 3.0 speed versus 2.0? What's the difference?

Anyway, I connected my second computer this morning through the USB-C and it seems to run just fine with full resolution and the USB peripherals (mouse/keyboard) works great.

Best regards,

Johannes

@Johannes SL  USB 2.0 is rated for 480 Mbps.  USB 3.0 is rated for 5 Gbps.  So if you had any USB peripherals connected to your display that actually used USB 3.0, such as an external hard drive/SSD, a fast flash drive, a Gigabit Ethernet adapter, etc., then they would perform better if they actually had a USB 3.0 data path all the way to your PC.  If on the other hand you plug a USB 3.0 peripheral into the display and it only has a USB 2.0 data path to your PC, then it will only perform at reduced USB 2.0 speeds.  If you only have a keyboard and mouse plugged in though, then don't worry about it.

Hi, jphugan,

Thanks for clarifying!

Yes, I only have keyboard/mouse, so it seems to work flawlessly.

The only thing I noticed is that my computer which connects through the USB-C does not seem to be charging/loading through the USB-C alone which  I thought it should be able to. Maybe a limitation from USB 3/2?

Regardless, not a big problem. I'll be testing the KVM functionality later. Either way this will be a huge improvement in my daily office life as I've been switching connections on a daily basis.

Thanks for all support and best regards.

Johannes

@Johannes SL  What type of system do you have?  Not all systems support charging via USB-C, and some require more power than the U4919DW provides.

We see that you are currently working with our Forum users. Send us a private message if you need further support.

That's probably the reason, then. Not a big problem anyway. 

So, I finally got to test this and it works great. Switching is a bit cumbersome. An actual switch would have been awesome. 

But overall this works great. I've been unplugging PC 1 and plugging PC2 back and forth for a few months now. Kind of annoyed with myself for not setting up this sooner. LOL. Better late than never, though.

Thanks for all help.

Best regards.

Johannes