I was successfully running two external monitors (not Apple Thunderbolt) from my 2015 MBP 13". They were both connected to the left side thunderbolt ports via HDMI to Thunderbolt cables. No problems.
I replaced one of the monitors and now both are the exact same monitor (ACER R240HY). The new one is not recognized. Cables are fine, when I swap thunderbolt ports the new monitor is recognized.
Cleared NVRAM, PRAM, and SMC. Didn't work.
Tried unplugging monitors and booting up with cables in first then plugging in monitor. Didn't work.
Searched and read threads for over an hour so asking here.
Thanks for any help!
Update per request:
- Old/replaced monitor (Viewsonic) works in either port by itself
- New replacement monitor works in only 1 port either by itself or with the original.
- Original monitor works in only 1 port either by itself or
with the replacement.
In other words, both ports work, all monitors work, all cables work, but the replacement monitor is just not recognized in one of the ports (but it is recognized in the other.)
SPECS
Original Two Monitors that worked
ACER R240HY – using HDMI to Thunderbolt Cable
Viewsonic VA2455 – using HDMI to DVI/Thunderbolt adapter
Replacement monitor
ACER R240HY – using HDMI to Thunderbolt Cable
Best Answer
So you're not connecting them exactly the same. You're using two adapters on the Viewsonic (an HDMI-DVI cable and an HDMI-Mini DisplayPort cable daisy-chained together) and one on the old Acer. Now you're trying to connect two via HDMI-Mini DisplayPort cables.
I would suggest trying to connect one of your Acer monitors using a normal HDMI cable to the HDMI port on the right side of the MacBook and the other to the left Thunderbolt port using the HDMI-Mini DisplayPort adapter.