Running into graphics card problems

1
I am encountering these messages from Psychtoolbox and I'm not sure how to correct this.

PTB-INFO: NVIDIA Corporation - GM204 [GeForce GTX 970] GPU found. Trying to establish low-level access...
PTB-INFO: Connected to NVidia GM204 [GeForce GTX 970] GPU of NV-110 family with 4 display heads. Beamposition timestamping enabled.
PTB-INFO: Many graphics cards do not support proper timing and timestamping of visual stimulus onset
PTB-INFO: when running in windowed mode (non-fullscreen). If PTB aborts with 'Synchronization failure'
PTB-INFO: you can disable the sync test via call to Screen('Preference', 'SkipSyncTests', 2); .
PTB-INFO: You won't get proper stimulus onset timestamps though, so windowed mode may be of limited use.
PTB-INFO: Fixed point precision integer framebuffer enabled.


PTB-INFO: OpenGL-Renderer is NVIDIA Corporation :: GeForce GTX 970/PCIe/SSE2 :: 4.5.0 NVIDIA 361.28
PTB-INFO: VBL startline = 1080 , VBL Endline = 1124
PTB-INFO: Measured monitor refresh interval from beamposition = 16.667167 ms [59.998201 Hz].
PTB-INFO: Will use beamposition query for accurate Flip time stamping.
PTB-INFO: Measured monitor refresh interval from VBLsync = 16.667087 ms [59.998489 Hz]. (58 valid samples taken, stddev=0.256153 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.

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.

Any suggestions?

2
You have a rather noisy timing on this system. Which OS, etc? But before you reply, have you tried all the steps suggested by the message:

On Tue, Apr 19, 2016 at 10:04 PM, rkopstick@... [PSYCHTOOLBOX] <PSYCHTOOLBOX@yahoogroups.com> wrote:
Please read 'help SyncTrouble' for information about how to solve or work-around the problem.

All the best,
Dee
3
I'm on Ubuntu 14.04 LTS 64-bit running Matlab R2015b (64-bit) academic user. I've tried a VBLSyncTest, and the calling Screen('Preference', 'SkipSyncTests', 2) before running my code. The SyncTest shows 0 missed stimulus presentation deadlines, and calling that Screen command doesn't solve the problem.