Monitor refresh interval problem - due to ignoring professional advice

Hardware
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1

Hello, I’d be happy to help. I’m trying to run a research using multiple monitors and an Intel graphics card with psychtoolbox. Unfortunately, I can’t switch to Linux.

When I run the code on a computer with two identical connected monitors, sometimes it works:
PTB-INFO: OpenGL-Renderer is Intel :: Intel(R) UHD Graphics 630 :: 4.6.0 - Build 30.0.101.1339
PTB-INFO: VBL startline = 1080 , VBL Endline = 1080
PTB-INFO: Measured monitor refresh interval from beamposition = 16.664753 ms [60.006890 Hz].
PTB-INFO: Beamposition queries are supported, but disabled. Using basic timestamping as fallback:
PTB-INFO: Timestamps returned by Screen(‘Flip’) will be therefore less robust and accurate.
PTB-INFO: Measured monitor refresh interval from VBLsync = 16.663696 ms [60.010696 Hz]. (50 valid samples taken, stddev=0.150842 ms.)
PTB-INFO: Reported monitor refresh interval from operating system = 16.666667 ms [60.000000 Hz].
PTB-INFO: Small deviations between reported values are normal and no reason to worry.

And sometimes it crashes:
PTB-INFO: OpenGL-Renderer is Intel :: Intel(R) UHD Graphics 630 :: 4.6.0 - Build 30.0.101.1339
PTB-INFO: VBL startline = 1080 , VBL Endline = 1080
PTB-INFO: Measured monitor refresh interval from beamposition = 16.664582 ms [60.007507 Hz].
PTB-INFO: Will use beamposition query for accurate Flip time stamping.
PTB-INFO: Measured monitor refresh interval from VBLsync = 16.688120 ms [59.922867 Hz]. (50 valid samples taken, stddev=0.397247 ms.)
PTB-INFO: Reported monitor refresh interval from operating system = 16.666667 ms [60.000000 Hz].

Does anyone know why this happens and if there’s something that can be done about it?

Additionally, when I run the experiment from a laptop with a different-sized additional monitor, I usually get different numbers for VBL STARTLINE and VBL ENDLINE, which affects the monitor refresh interval, and the code crashes…:frowning:

Does anyone have any advice or insights?

Thank you

2

It almost certainly doesn’t work with an Intel graphics chip under Windows if you care about timing as you stated. Regardless if you use Psychtoolbox or any other software for stimulus presentation. The cases where you think it works are almost certainly just false positives, as the tests are not perfect in catching all error cases - just better at detecting trouble than what other toolkits have. Read what was written in response to your other question. If the welcome screen “vibrates” ever then you are out of luck.

As you apparently can’t upgrade to Linux, get a different graphics card from AMD or NVidia and pray that that works better - not guaranteed (especially not on multi-display) but more likely.

3

Thanks. Which Linux distribution is recommended to psychtoolbox?

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4

this will answer that for you: http://psychtoolbox.org/requirements.html#linux

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