U2518D, D3100, Inspiron 15 5502, refresh rate locked to 24Hz

Before our users can assist in troubleshooting, they need more data =

* What specific Dell monitors?
* What specific PC model?
* What operating system is running on the PC?
* What specific video card/GPU is installed in the PC?
* List all of the video card/GPU video out ports
* List in detail how the monitors are connected to the D3100 using all ports and cabling

@yeeleunglee  Sounds like a bandwidth limitation of the very old DisplayLink chipset used in the D3100. I believe that dock is only rated for dual 1080p displays, but you have no information about the displays you’re using or your laptop other than that it’s a Dell. But you can try updating the DisplayLink drivers directly from DisplayLink.com, but if that doesn’t fix it, then as mentioned above, when asking for technical assistance it helps to provide basic technical information.

@yeeleunglee  Actually, I just noticed that the U2518D supports DisplayPort daisy chaining.  So here's another much simpler and less expensive way you can get both displays running properly and avoid DisplayLink's drawbacks.

• Get a USB-C to DisplayPort cable, and also a regular DisplayPort cable if you don't already have one (though the U2518D should have come with one).
• Use the USB-C to DP cable to connect the USB-C port on your system to the DisplayPort input of one of your U2518D displays.  Set this display to its DisplayPort input.
• Use the DisplayPort cable to connect the DisplayPort output of that first U2518D to the DisplayPort input of the second U2518D.  Set this display to its DisplayPort input as well.
• On the first U2518D, enable MST mode in the display's onscreen setup.

Make sure you don't mix up DisplayPort input and output connectors on either display, otherwise this won't work.  But once you get it running, you'll have both displays running at 60 Hz and running natively from your GPU rather than through DisplayLink.

Thanks for the response. The dell laptop is a dell 15 5502 purchased in Nov 2020 and the dell monitors are 2x dell U2518D with the latest firmware (M2T103) and running at 2048x1080 using a D3100 which has the latest display link driver (v9. 3.3324.0 (10.2.3)). I hope that this provides the information you need to provide a resolution?

@yeeleunglee  Well that's certainly an improvement, but it isn't a fix.  Again, the U2518D has a native resolution of 2560x1440, not 2048x1152.  Running a 2560x1440 display at 2048x1152 resolution means you'll have less workspace than you should AND you'll see scaling artifacts because a 2048x1152 signal does not map cleanly onto a 2560x1440 pixel grid as found in your displays.  You're especially likely to notice this on text, which will appear fuzzier than it should.  And there's also the fact that running that way means you're simply not using the full capabilities of the displays you paid for.  The reason Windows is "recommending" that resolution here is because the dock won't support anything better, not because it's actually a good solution.

I would recommend getting a dock that can run your displays at their proper native resolution.  If you don't care about 2560x1440 resolution, then you could have saved yourself some money and just gotten 1920x1080 displays.  That would give you almost the same pixel area you're using now, and you wouldn't have any scaling quality issues that you're having now.  But since you paid for 2560x1440 resolution, you should get a setup that will allow you to use it.