Hello! It sounds like you want to use the KVM functionality of your Dell U4919DW monitor to switch between two PCs and have different display settings for each PC. Here's what you can do:

1. Connect both PCs to the Dell U4919DW monitor using the appropriate cables.

2. Enable KVM functionality on the monitor by going to the "Input Source" menu and selecting "KVM."

3. Set up PC one to use HDMI1 as the input source and set the display settings to fill the whole screen.

4. Set up PC two to use both HDMI2 and DP as input sources and enable Picture-by-Picture (PBP) mode. This will split the screen into two equal halves, with each half displaying the output from one of the input sources.

5. Use the KVM switch button on the monitor to switch between the two PCs. When you switch to PC one, it will display in full screen mode. When you switch to PC two, it will display in PBP mode, with each input source taking up half of the screen.

6. Use the same keyboard and mouse to control both PCs by connecting them to the USB upstream port on the monitor.

Note that you may need to adjust the display settings on PC two to ensure that it is outputting at the correct resolution and aspect ratio for PBP mode on the Dell U4919DW monitor.

I hope this helps! Let me know if you have any other questions.

This is exactly what I want to do - but have not been able to achieve.  I tried to follow your suggestions - and get hung up almost immediately.

You say in step 2 to choose KVM as the input source.  If I go to the input source on the monitor I can choose between Auto, USB Type-C, DP, HDMI1, HDMI2 - there is no choice for KVM.

I have not figured out a way to have PC1 use 1 input source and PC2 to use 2 input sources with the simple flip of the KVM.

You three PC setup is not possible because we only provided one USB-A to USB-B upstream cable.

Input Source HDMI 1 =
PC #1 HDMI out --> U4919DW HDMI to HDMI cable --> U4919DW HDMI 3-1 in port
PC #1 USB-A --> U4919DW USB-A to USB-B upstream cable --> U4919DW 6-1 USB-B upstream port

Input Source HDMI 2 =
PC #2 HDMI out --> retail HDMI to HDMI cable --> U4919DW HDMI 3-2 in port
PC #2 USB-A --> retail USB-A to USB-B upstream cable --> U4919DW 6-2 USB-B upstream port
PC #3 DP out --> retail DP to DP cable --> U4919DW DP 4 in port

Then see online U4919DW User's Guide page 51-53 to use PBP On, PBP (Sub) DP.

Chris - I'm not looking for a 3 PC setup.  Please re-read the first two posts for clarity.

PC1 should use HDMI1 and be full screen

PC2 should use HDMI2 and DP and be in PBP mode.

I would like to seamlessly flip between those two modes.

Possible or not?

I see, no, that is not possible to use multiple video out ports from the same single video card for PBP. PBP is using two PC, two video card sources.

Chris - I still think we have a misunderstanding...  I am not looking to split a single video output.

PC2 has - and supports - multiple video outputs - and can drive two physical monitors, thus it can also drive two logical monitors in PBP.

I have no issues setting up PC1 to drive the 49" monitor as a single monitor.

I have no issues setting up PC2 to drive the 49" monitor as two logical monitors (PBP).

I do have difficulty setting up the KVM to flip easily between the two setups above.  Please advise.