I have a MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports) version 10.14.5.
A first monitor (DELL P2719HC) is connected through thunderbolt 3 while a second monitor (DELL E2313H) is connected through a VGA adapter. The latter is the one flickering!
Flickering stops when I disconnect the first monitor. Thus, it's not a problem of the adapter, nor the screen. I am guessing this is due to my laptop not being able to give enough fps to both screens (they both require a 60Hz refresh rate at minimum, which I cannot change event with some command line tools).
I tried to reset VRAM and SMC, but it did not work.
What else can I do?
Best Answer
This problem is not due to the computer not being able to serve the necessary amount of "fps". Instead this is a hardware problem.
VGA is an analog signal. If the signal is distorted or interfered with, it could problems such as flickering. The flickering stops when you disconnect the first monitor - which indicates that this monitor (and cable) is the source of interference.
I would suggest replacing the VGA cable with one with a ferrite bead instead. Another option is to replace the VGA adapter with a DVI adapter and connect to the monitor using a DVI cable.
If possible you could also try to the cables seperate from each other physically (i.e. get distance between them) - but it is difficult as they need to plug in to the computer very near each other.