S2421HS, cannot set up using HDMI into PC USB Type-C

Question

Hi Apologies if this is already covered elsewhere but I am new to the forum and couldn't find the answer in the FAQs or other discussions. I have bought a Dell Inspiron 3881, which has 1 HDMI port, 1 DisplayPort, and a USB 3.2 Gen Type-C port. I have three monitors: 2 x S2421H (with HDMI out) and 1 x S2421HS (HDMI and DisplayPort) I have attached one of the S2421H monitors into the HDMI port and the S2421HS into the DisplayPort with no problem. However, I am trying to attach the other S2421H into the USB Type-C port using an HDMI adapter (from Syntech) with no success - the monitor is not recognizing any signal. I had understood that this should work (which is why I bought this set-up). Am I doing something wrong? Any advice would be very gratefully received. Many thanks

jphughan · Accepted Answer

@FredNW11 Glad to hear things have improved, but sorry to hear you're not quite there yet. When you say "third monitor", how is that one connected? I'm guessing you have two displays connected via the MST hub and the third connected via the HDMI output, but which connection is the problem display using at the moment? Does the problem disappear if you disconnect either of the OTHER two displays? Admittedly the answers to those questions shouldn't matter given that you're only trying to run triple 1080p, and the earliest DisplayPort revision that supported MST also supported enough bandwidth for 4K 60 Hz, which is equivalent to quad 1080p all run from that single output. So dual 1080p from an MST hub is very well within what should be achievable through that DisplayPort output.

Also, have you updated your system BIOS and GPU drivers? And have you tried configuring your display setup using the GPU's own control panel application rather than Windows Display Settings? I'm talking about something like Intel Graphics Control Panel, or NVIDIA Control Panel, or AMD Catalyst, depending on which GPU controls the outputs you're working with.

FredNW11 · Answer

Thanks for the reply. Is there any way I can use a third monitor with this system, in that case? Fred

jphughan · Answer

@FredNW11 I forgot to add that there's some good news here. Your DisplayPort output is capable of running multiple independent displays from a single source port. The simplest way to achieve this is with displays that support DisplayPort daisy chaining, but yours don't. The next easiest method is with a device called a DisplayPort MST hub. They plug into a DisplayPort output and give you two or more DisplayPort and/or HDMI outputs. DisplayPort outputs are more common since after all you're plugging into a DisplayPort output, but if only one of your displays has a DisplayPort input, then that won't work. And conventional passive DP to HDMI cables/adapters don't work with most MST hubs. Active cables would, but they cost more. So I would instead suggest that you get an MST hub that has dual HDMI outputs, like this one, and then connect your third HDMI display to the system's built-in HDMI output.

It's either that or get a different system, or at least a different GPU.

jphughan · Answer

@FredNW11  Video output over USB-C requires an actual GPU output to be wired to that port. That is an optional feature of USB-C ports and as such is not always implemented on systems that have USB-C. Typically on Dell systems that have it, their specs mention that capability, but your system’s USB-C port description indicates that it only works as a conventional USB 3.x port.

FredNW11 · Answer

Thank you for the reply. Just to confirm before I buy this hub, the link above seems to take me to a product with HDMIs outputs going into a UBS-C port. I had understood from what you wrote that I need something that uses the DisplayPort?

Thanks again

jphughan · Answer

@FredNW11  I apologize, I do indeed seem to have linked the wrong product for your purposes.  Here is an MST hub that plugs into a DisplayPort input and gives you two HDMI outputs.

FredNW11 · Answer

Hi

OK, I have bought the MST hub and have partial success in that all three monitors are now displaying something. The last remaining problem is that the third monitor has the wrong resolution - the display is all super-sized. On display setting I am unable to change the resolution. Is there anyway to fix this, please?

Many thanks,

Fred

FredNW11 · Answer

Thanks - I swapped one of the S2421H monitors (in the hub) with the S2421HS that was previously connecting directly into the HDMI port, and that seems to have done the trick.

Many thanks for all of your help.

Fred

Monitors

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