I have a Dell Inspiron 17 with an embedded 620, along with a GeForce MX150. I have a USB-C to 2 HDMI ports adapter which can successfully connect 2 external displays to the laptop. If I plug a third display into the HDMI port. it will activate, but one of the displays attached through the UCB-C adapter goes inactive. Is there a driver switch or update that will let me attach 3 external displays in addition to the native laptop screen?
Alternatively, will the 620 support attaching 2 external displays each at 2560x1440?
Regardless of how many monitors you hook up, Intel UHD Graphics 620 supports a maximum of three displays simultaneously. A fourth could be added to your laptop using a USB3 graphics adapter. Here is one that supports that 1440p monitor: https://www.amazon.com/gofanco-Multiple-Displays-External-Graphics/dp/B01GSW3K96?th=1.
You can connect two 1440p monitors to the USB-C connector. The connector is exposing a DisplayPort 1.2 channel which has a bandwidth of 17.28 Gb/s. Two 1440p monitors running at 60Hz requires a bandwidth of 11.26 Gb/s. Since I do not know what MST Hub you already have, I cannot say for certain that it supports this bandwidth. This one certainly looks like it can: https://www.amazon.com/Adapter-Converter-Compatible-MacBook-Samsung/dp/B07QKVY23Q.
Hope this helps,
Thank you very much for the quick response, I was afraid of the answer, dang. I do have the exact adapter you listed, it arrived today and I immediately tried it out, leading to my question(s). Tomorrow I am receiving a display stand that is supposed to be able to support 3 monitors, and a new 1080p monitor to replace a tired old one, thankfully both have free returns. Now I need to decide if I will upgrade to two 32" 1440p monitors, or add a USB to display adapter and go with the three 1080p's and the fancy display stand. At least now I know I have a choice. Thanks again!