It is also important to have a distinction:flood wrote:and for me, even if I use the same refresh rates, the displays are still not synchronized.
"The two outputs are not synchronized with each other" (signal output lag: both frames not being output simultaneously)
Versus
"The monitor refreshes are not synchronized in the camera photo" (monitor lag)
That is what I mean. If tearlines are different positions for the SAME frame number, you got unsynchronized outputs, as if two asynchronous page flips are occuring at different times inside the GPU (e.g. Two separate indepdent framebuffer chains running in parallel in the drivers). It is possible to run separate front buffers in the driver software, one for each cloned output, to permit different refresh rates for different cloned output. This causes input lag differences between the cloned outputs. Different tearline positions for the SAME frame number, is a telltale sign of this occuring. To avoid this malarkey hooey, you need to use a splitter, or do careful tests that the cloning is in sync (at the signal output level, nothing to do with the monitor), before trusting cloned output.
It is important to interpret the results correctly.