Connecting 2 External Monitors

@OrchardRock  Are you sure that your system's USB-C port supports video output?  That is an optional capability of USB-C ports and not implemented on all systems.  Unfortunately I don't know which system you have because "Inspiron 15 7000" is the name of an entire model SERIES that includes multiple models introduced over multiple years.  It's a bit like saying you have a "BMW 3 Series".  There are lots of different models that fit that description.  Your exact system model would be something like Inspiron 7578, for example.

Hi @jphughan,

The exact model is an Inspiron 7586.

Thanks.

@OrchardRock  ok, the Setup and Specifications document for that system available on support.dell.com (direct link here) indicates that the USB-C port supports video output.  It notes DisplayPort, but that's normal for USB-C since that's what USB-C ports use for video.  A USB-C to HDMI adapter would contain an active converter chip to switch that DisplayPort signal to HDMI.  Have you confirmed that this second display and the cable you're using it with works properly when connected to your system's built-in HDMI port, just to rule out an possible issue with the second display and/or the cable it's using?  If that works, then have you confirmed that the USB-C to HDMI adapter works elsewhere?  If not (or actually even if you have), I would suggest trying a different USB-C to HDMI adapter.  The reason I said "even if you have" is because just a few weeks ago I was working with someone who was having trouble with this exact type of setup, although on a different system.  And he had even confirmed that the USB-C to HDMI worked when used with a separate source system.  After some troubleshooting, I basically said that this was either a strange interoperability problem between his specific adapter and his specific laptop that shouldn't exist but might anyway, or else it might be a problem with his motherboard that was preventing video output over USB-C (he didn't have another adapter to test that).  Then I added that since a motherboard replacement would be a huge ordeal and that sometimes those interoperability problems crop up even though they shouldn't, he may want to try just getting a different brand of USB-C to HDMI adapter.  He did, and the other brand worked with both his laptop and the original device that was working with the first one.

@jphughan 

Yes my second monitor and HDMI lead work when directly connected to my HDMI port. From what you have said it looks like I have bought the wrong connector. I have a USB to HDMI and it sound like I need a USB-C to HDMI. I'll buy one and see if that works.

Thanks, you've been very helpful!

@OrchardRock  Ah ok, so you have an adapter that plugs into a regular USB port?  Those require additional software in order to work because regular USB ports do not natively work as video outputs.  But even if you install that extra software, the "indirect display" technology that has to be used in order to send video out of a regular USB port can come with some potentially serious drawbacks.  They're a decent solution if that's your only option because your system simply doesn't have any other native video outputs, but that isn't the case here.  So yes I would get a USB-C to HDMI adapter or cable, since your USB-C ports actually CAN have a native video output wired to them, and your system has that.

Just as a general tip for future reference, when asking about technical questions like this, it might be helpful to provide exact model names or links to the products involved.  It might reduce confusion and thus time spent going in the wrong direction.