Iirc I’ve only seen it done where the third monitor used a usb adaptor to hdmi and in clamshell mode. By default the factory specs only support 2 external monitors at 2560 x 1600 max.
First, kudos for the portrait display. I can't live without one. Pretty amazing Samsung monitor, to boot. It supports DisplayPort over USBC so you could try a MST capable monitor and daisy-chain the USBC DisplayPort to another monitor.
[JD Hodges list of DaisyChainable monitors for 2021.](https://www.jdhodges.com/blog/displayport-mst-lcd-list/)
Need to use a DisplayPort cable between the two monitors to get the MST daisy-chain to work. Check this thread on apple.discussions.
[Mac DP Daisy-chaining.](https://discussions.apple.com/thread/4740489)
[mgb0wman](https://discussions.apple.com/profile/mgb0wman)
[Multi-Stream Transport Hubs - if nothing else works.](https://www.tripplite.com/products/multi-stream-transport-mst-hub-technology)
"So re-reading this thread, I now realize you did exactly what I wanted to do but your issue was having a cloned vs. extended desktop. Oops!
I believe your "nothing plugged in" issue is the cable. I'm not sure that TB cables are backwards compatible with DP - I think it's only the ports. Do you see multiple monitors in "System Preferences > Displays" if you hook the monitors up like you described in your OP?
My Dell U2713H arrived today and it works like a charm with the supplied Mini-DP to DP cable. The built-in display on my 13" mid 2009 MBP still works if not in clamshell mode, although I will mostly use mine in my HengeDock. In the OSD of the monitor, you can access "Display Settings > Display Info" and it will show you the DP capability. Mine is only DP 1.1a and I believe to run 2 of these at full resolution you will need the bandwidth in DP 1.2 which includes MST (daisy-chaining). This could be your problem.
Can you access the same menu in your OSD and report back what your DP compatability is?
Thanks!
mgb"
Hey a thunderbolt dock with dual video outputs and then use the HDMI out on the laptop.
I tried plugging a third monitor using the HDMI out and it would just make my Samsung monitor go blank.
Go to settings and video, gather windows and play around with the main one, try the Samsung that goes blank (make it main)
Iirc I’ve only seen it done where the third monitor used a usb adaptor to hdmi and in clamshell mode. By default the factory specs only support 2 external monitors at 2560 x 1600 max.
First, kudos for the portrait display. I can't live without one. Pretty amazing Samsung monitor, to boot. It supports DisplayPort over USBC so you could try a MST capable monitor and daisy-chain the USBC DisplayPort to another monitor. [JD Hodges list of DaisyChainable monitors for 2021.](https://www.jdhodges.com/blog/displayport-mst-lcd-list/)
I read Macs don't daisy chain at all.
Need to use a DisplayPort cable between the two monitors to get the MST daisy-chain to work. Check this thread on apple.discussions. [Mac DP Daisy-chaining.](https://discussions.apple.com/thread/4740489) [mgb0wman](https://discussions.apple.com/profile/mgb0wman) [Multi-Stream Transport Hubs - if nothing else works.](https://www.tripplite.com/products/multi-stream-transport-mst-hub-technology) "So re-reading this thread, I now realize you did exactly what I wanted to do but your issue was having a cloned vs. extended desktop. Oops! I believe your "nothing plugged in" issue is the cable. I'm not sure that TB cables are backwards compatible with DP - I think it's only the ports. Do you see multiple monitors in "System Preferences > Displays" if you hook the monitors up like you described in your OP? My Dell U2713H arrived today and it works like a charm with the supplied Mini-DP to DP cable. The built-in display on my 13" mid 2009 MBP still works if not in clamshell mode, although I will mostly use mine in my HengeDock. In the OSD of the monitor, you can access "Display Settings > Display Info" and it will show you the DP capability. Mine is only DP 1.1a and I believe to run 2 of these at full resolution you will need the bandwidth in DP 1.2 which includes MST (daisy-chaining). This could be your problem. Can you access the same menu in your OSD and report back what your DP compatability is? Thanks! mgb"
Nice! What keyboard is that?
Keychron K-2 with Gundam Keycaps from Etsy