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2 screen window flips ignores waitBlanking?

On a Win10 machine (PsychoPy v2021.2.3) with 2 screens I try to do an animation on both screens. On one window I use waitBlanking=True to keep track of the time, on the other waitBlanking=False to not disturb the time tracking of the other screen.
Problem is animation runs only smooth when running on one screen at a time.
screen0 or screen1 animation: does run smooth
screen0 and screen2 animation: does not run smooth
The waitBlanking attribute does not make any notable difference. I run the routine in Windows realtime mode.

Is the onboard Intel graphics chip the problem?
Thanks!

(Win10 64 bit Enterprise, IntelCore i7-8700 cpu 3.19GHz, 16GB RAM, Onboard Intel UHD Graphics 630, 2 HD monitors, Python 3.6.6, OpenGL version: 4.5.0 )

The intel graphics maybe slower than a dedicated graphics card, but that may not be the limiting factor here, depending on how complicated the animation is. Do you have access to a computer with an nvidia graphics card you could test on? It would be a shame to spend $$ on upgrading your graphics card if it ends up not making any difference.

If the project is something you can share, maybe you could post it and someone with a dedicated graphics card might be able to try it out and report if they see jitter or not.

Great idea sol!
Here is my short example code:

test2win.py (2.1 KB)

Much appreciated if someone with an dedicated graphics card could test it…

I have a Dell G5 laptop with a nvidia 1060 4GB video card I don’t visually see any difference between the dot moving on 1 screen vs 2 screens (by using the ‘1’ and ‘2’ keys) in your demo.

Is it very obvious that the dot is jittering / jumping for you when both screen are used?

Thanks for trying!
Yes, the jittering is clearly visible for me when using 2 screens.
If you use waitBlanking = True for both windows can you see jitter in that case? Or does the movement slow down?

If I switch it to waitBlanking=True for both windows, then win1 starts looking choppy compared to when win1 was created with waitBlanking=False

Ok, for me that makes no difference at all, always choppy.

I guess the conclusion is that the problem is the onboard graphics chip.

Thanks ,for helping me out!
Frank