Cable recommendation for HDMI display

Question

I am a bit lost on what adapters and cables I need for connecting a second external monitor to my laptops.

I already have an external HDMI monitor. All my three laptops have HDMI ports with which I am able to use this external monitor (using HDMI male-to-male cable). I want to connect one more HDMI monitor now as a second external display (ideally to any of my three laptops). All three laptops run Windows 10.

All three laptops have multiple USB 3.0 (SS) ports. They all have mini display ports (I believe I am using the correct term) as well, but one of them seems to have a different kind. Please see images below.

Laptop 1: The port on the left above is what I think is the mini display port.

Laptop 2: This laptop has the same kind of display port as laptop 1.

Laptop 3:

I am not sure if the left most port in this image is the same as the left most ports in above two. It doesn't have the two + symbols like the ones above have. Is it the same as the ports in the first two laptops?

Not realizing that I have these mini display ports, I purchased "Plugable USB 3.0 to DisplayPort 4K UHD" from Amazon (for $60), which has a male USB 3.0 and a female full-sized Display port. I believe that I now need a display port to HDMI adapter to connect to the external monitor. Would it be better to return this adapter and purchase a different one?

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UPDATE: I don't really need HDMI for my second external monitor, since it also has a VGA port. I ended up purchasing a USB 3.0 to VGA adapter, which costs only $16. All my laptops have at least one spare SS port, so I am good now.

Answer 1

Get a passive Mini DisplayPort to HDMI cable, like this one

As SiXandSeven8ths mentioned, DisplayPort++ (also known as Dual Mode) is a technology that allows DisplayPort to put out another signal for use with passive adapters. While limited because of this unidirectionality, it's an incredibly cheap, easy, and effective solution for what you're trying to do. Though it's difficult to confirm with your third laptop, almost all laptops with Mini DisplayPort support this mode because of its extreme popularity and utility–even when not indicated, like on the XPS 13.

One thing worth noting is the Thunderbolt 3 connection on your third laptop. Thunderbolt 3 (and USB-C, which can also carry a DisplayPort connection) cannot utilize DisplayPort++ because it lacks the necessary pin count to do so.

While your solution of using a USB to VGA graphics adapter works, I would advise against this in the future. VGA is a much more limited connection, namely in that it is an analog rather than a digital signal.