Psychtoolbox SyncTests error (windows 11): Trouble with VBL syncing/VBL not working

Bugs & Features
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1

Hello everyone! I am programming a SSVEP experiment which is time-sensitive, so I cannot skip the SyncTest. The scripts worked well with SkipSyncTests=1, but when I tried to do the SyncTest, it reports warnings and the experiment could not run.

For your information, the version of Psychtoolbox is 3.0.19, windows 11 (I cannot change it to linux because someone else is using the same laptop), with a hybrid graphics (Intel Graphics and the NVIDIA RTX 500 Ada GPU) and a separate monitor; I’ve tried all settings mentioned in help syncTrouble (tripplebuffering, vertical sync) and disabled the variable refresh rate; I also tried to the main display and scale, but none of these attempts worked. Sometimes when the laptop wasn’t connected to the monitor, it could run with successful SyncTest (but during most of attempts, it still failed with exactly same settings), but as long as it was connected to the monitor, there were always failures with SyncTests.

I’ve tried to read many discussions but none of them could solve the problem. I hope you guys could help solve the problem and I will really appreciate that.

Here is the warning information:
Experiment about to start. Note that you can abort at any time
by pressing the ESC key as a response to any of the questions.
Using screen 2 of 2.

PTB-INFO: This is Psychtoolbox-3 for Microsoft Windows, under Matlab 64-Bit (Version 3.0.19 - Build date: Jul 31 2024).
PTB-INFO: OS support status: Windows 11 (Version 11.0) is not supported.
PTB-INFO: Type ‘PsychtoolboxVersion’ for more detailed version information.
PTB-INFO: Most parts of the Psychtoolbox distribution are licensed to you under terms of the MIT License, with
PTB-INFO: some restrictions. See file ‘License.txt’ in the Psychtoolbox root folder for the exact licensing conditions.

PTB-INFO: For information about paid support, support memberships and other commercial services, please type
PTB-INFO: ‘PsychPaidSupportAndServices’.

PTB-WARNING: Couldn’t determine end-line of vertical blanking interval for your display! Trouble with beamposition queries?!?
PTB-WARNING: Detected end-line is 2159, which is either lower or more than 1.250000 times higher than vbl startline 1620 → Out of sane range!

PTB-INFO: OpenGL-Renderer is NVIDIA Corporation :: NVIDIA RTX 500 Ada Generation Laptop GPU/PCIe/SSE2 :: 4.6.0 NVIDIA 566.03
PTB-INFO: VBL startline = 1620 , VBL Endline = 2159
PTB-INFO: Beamposition queries unsupported or defective on this system. 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 = 16.668464 ms [59.993530 Hz]. (50 valid samples taken, stddev=0.418871 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.
PTB-INFO: ==============================================================================================================================
PTB-INFO: WINDOWS DWM DESKTOP COMPOSITOR IS ACTIVE. On this Windows-10 or later system, Psychtoolbox can no longer reliably detect if
PTB-INFO: this will cause trouble for timing and integrity of visual stimuli or not. You might be just fine, or you could be in trouble.
PTB-INFO: Use external measurement equipment and independent procedures to verify reliability of timing if you care about proper timing.
PTB-INFO: ==============================================================================================================================

WARNING: Couldn’t compute a reliable estimate of monitor refresh interval! Trouble with VBL syncing?!?

----- ! PTB - ERROR: SYNCHRONIZATION FAILURE ! -----

One or more internal checks (see Warnings above) indicate that synchronization
of Psychtoolbox to the vertical retrace (VBL) is not working on your setup.

This will seriously impair proper stimulus presentation and stimulus presentation timing!
Please read ‘help SyncTrouble’ for information about how to solve or work-around the problem.
You can force Psychtoolbox to continue, despite the severe problems, by adding the command
Screen(‘Preference’, ‘SkipSyncTests’, 1); at the top of your script, if you really know what you are doing.

2

Hello

That’s exactly the kind of hardware we do strongly recommend against for proper timing (Psychtoolbox-3 - System Requirements). See help HybridGraphics for more info and troubleshooting tips.

Unless you get very lucky, it is not very likely that this is salvageable under MS-Windows at all, if timing is of any importance. Depending on the exact hardware configuration of your Laptop, it is possible that it could be solvable under Linux, again depending on specific hardware either easily, or with some effort. You can install Linux as a dual-boot rather easily on most laptops, by shrinking the Windows partitions on the internal harddrive and installing Linux into the free space, or even install Linux on an external USB disc drive and dual-boot that way.

That’s all good, and in general only a display scaling factor of 100% ie. no scaling at all will be workable on MS-Windows. But it doesn’t solve all the hybrid graphics related problems on Windows.

That’s good, as your lab can express its appreciation by buying a paid support membership and presenting a support authentication token for up to 30 minutes of my paid support, just as PTB told you here:

PTB-INFO: For information about paid support, support memberships and other commercial services, please type
PTB-INFO: ‘PsychPaidSupportAndServices’.

→ help PsychPaidSupportAndServices

Iff the problem is solvable under Windows at all (usually not), or if it would be solvable under Linux, depends on the specifics of your laptop, so apart from a paid support token, I’d need detailed information about the exact model and hardware configuration of your Laptop.

No guarantees though, the hardware is a very bad choice for visual neuroscience.

Best,
-mario

3

Hi Mario,

Thanks a lot for your quick reply! I understand these hybrid graphics hardwares are not recommended- I’ve checked help Hybrid Graphics already and found that the nouveau driver which is recommended couldn’t be used in Windows.

I will discuss with others who are gonna use this laptop to see if there is room for dual-boot.

Thanks again for your suggestion! I will let you know if I need more help.

Best,
Wenyu

4

Hi Mario,

Sorry to bother again. I just want to ask if you have any specific recommendations for hardware that would be suitable for visual experiment? Ideally, I would prefer a laptop setup if possible, but please let me know if a desktop would be necessary for optimal performance.

Thank you again for your assistance! I really appreciate it!

Best,
Nora

5

Laptops are generally fine. Specifics depend on the specific use case. Similar questions have been asked and answered many times on the forum → Search the forum for recommendations or experiences of others.

If you want to use Linux, search the internet for the model you have in mind or suitable models and Linux compatibility. Usually, not too exotic/unusual/brand new laptops from brand vendors are just fine. Or buy from one of the established Linux laptop vendors.

Some Intel laptops with very recent processors may not have working webcams with all recent Linux distributions out of the box without a manual Linux kernel upgrade or possible other manual software upgrades, if webcam support is a need, as they use some new types of Intel IPU6 imaging processors, cfe. https://www.phoronix.com/news/Intel-IPU6-Media-In-Linux-6.10

Most important is choice of graphics card brand ()

  1. If you only want to use Linux, preference order is : AMD > Intel >> NVidia.
  2. If you only want to use Windows (not recommended): AMD or NVidia. Under no circumstances Intel graphics, timing on Intel is almost always badly broken due to Intel drivers enforcing triple-buffering!!
  3. If you want to use both Linux and Windows optimally: AMD > NVidia.

On Linux, AMD has the advantage of more features like VRR/FreeSync tested for PTB’s fine-grained timing support on VRR/FreeSync capable monitors, which can be interesting for SSVP, HDR-10, up to 12 bpc color precision output, more extensive multi-display, higher performance.

Any further questions will require paid support.