Unable to Sync: MacPro + Propixx Projector?

Hi all, I am having some synch issues:


Problem: 

Periodically, the system will fail synch tests in code, apart from my own code, also the standard tests such as

- OSXCompositorIdiocyTest

- VBLSyncTest

- ProceduralGarboriumDemo

Once in a while it will work but not often.. and I don't know why.
I've contacted Vpixx support but they have no idea why either.. so any help appreciated. 



Setup:

Mac Pro (late 2013) 3.7G Xeon with 12G RAM and Dual AMD FirePro D300 2048Mb

Mac OS 10.12.4

Matlab 2016b

Psychtoolbox version 3.0.14 - Flavor: beta - Corresponds to SVN Revision 7911 but is *locally modified* !

ProPixx projector from VPixx, running at stock 120Hz mode connected to the MacPro via an Accell connector.



Attempted Fix:

So far i've tried:

- reinstalling Kernel kext

- PsychTweak('UseGPUIndex', 1)

- Screen('Preference', 'ScreenToHead', 1, 1, 1);

- Rebooting the computer. 

 

Error messages:

 

PTB-INFO: This is Psychtoolbox-3 for Apple OS X, under Matlab 64-Bit (Version 3.0.14 - Build date: May 12 2017).

PTB-INFO: Support status on this operating system release: OSX 10.12 minimally supported and tested.

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: OpenGL-Renderer is ATI Technologies Inc. :: AMD Radeon HD - FirePro D300 OpenGL Engine :: 2.1 ATI-1.50.38

PTB-INFO: Renderer has 2048 MB of VRAM and a maximum 1957 MB of texture memory.

PTB-INFO: VBL startline = 1080 , VBL Endline = -1

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 = 8.350583 ms [119.752118 Hz]. (563 valid samples taken, stddev=0.381606 ms.)

PTB-INFO: Reported monitor refresh interval from operating system = 8.333333 ms [120.000000 Hz].

PTB-INFO: Small deviations between reported values are normal and no reason to worry.

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.