I recently did a clean install of Windows 10 (1909). Before the reinstall, I could use an external 4k monitor at 60hz using a USB-C to HDMI 2.0 cable. Now, 30hz is the most it will do using the same setup as before. I updated the BIOS to 1.18.0 just before the reinstall. I installed all the latest drivers from the Dell Support site after the reinstall. I installed the Intel & nVidia display drivers directly from their sites. (Side note: the Intel Display driver on the Dell Support site says it doesn't support this version of Windows) My theory is that this has something to do with the laptop not using the nVidia GPU to drive the external monitor. When I look at the nVidia Control Panel, it only shows the Manage 3D settings, and when I look at the Windows display properties, it shows the the external display is connected to the Intel HD Graphics 630. How can I get back to running the monitor at 60hz?