Resolved Video playback stops GTX 960 Mac Pro 5.1

[Kaspersoerensen]

Hi there,

I have a MacPro 4.1 flashed to 5.1 running High Sierra. The firmware update and installation of HS went smooth. After this update however, my GTX 960 will stop video playback when using for instance youtube. The first frame of the video will load and it is possible to scroll through the timeline, but the video will not play. It just shows a wheel spinning, as when a youtube video is loading before playing (see attachment)
Just following a reboot video playback works. I have tried to reset PRAM.

Opening a video file (.mov) works fine.

The latest nVidia driver is installed. I have the original GT 120 in the mac together with the GTX 960.

Also, the Mac seems to randomly log me out, causing all unsaved work to be lost.

Any experience of the same and possible solutions for this? Also, if I need to provide any additional information, please give me a heads up.

Regards
Kasper

 

[ActionableMango]

Many people have reported problems running dual video cards with the more recent Nvidia drivers. So try removing the GT120.

If that doesn't fix the problem and your computer is still crashing, it would help to post the Kernel Panic log text. Otherwise there is no way to tell what is wrong other than guesswork like I've done above.

 

[Kaspersoerensen]

Yes indeed. Removing the GT120 solves the problem it seems (after almost a full workday with no log out).

 

[Kaspersoerensen]

An update to this.
There is still a problem with video playback, when removing the GT120 card. It seems to stop working after the computer has been at "sleep" mode.

 

[ActionableMango]

I don't think it's the Nvidia drivers or many many people would be complaining about not being able to use Youtube. So I don't know what to suggest other than typical troubleshooting things like trying a different browser, removing any plug-ins/add-ons you might have, trying a fresh install of MacOS, etc.

If it is crashing, post the Kernel Panic log.

 

[Kaspersoerensen]

That is a good point.

The video play back not only stops after sleeping (but also just when the computer is left on for some time.
Tried Safari and Chrome. Tried uninstalling flash and installing it again, with no success.

The computer is no longer crashing.

Update:
Turns out it was my external sound card that caused the problems.