Graphics card goes to sleep after a few minutes (e.g. in the middle of movies)

NVIDIA

#1

I have an old dual-core desktop with a Nvidia GT430 graphics card (using open source driver) that I use to play movies and music. Monitor is a 50" LCD connected with HDMI. After several minutes, the screen goes blank and audio goes silent even though I have the MATE screensaver set to never turn on. I found nothing in nvidia-settings that would suggest the graphics card has its own screensaver, and I am at a loss to explain it.

Clues:

  1. MATE screensaver is set to never come on (unchecked activate screensaver). The problem persists even if I set it to activate in 2 hours. Also, the MATE screensaver is not set to blank screen, which is what I see.
  2. The screen and sound instantly return when the mouse is moved. However, the issue occurs even if there is movement on the screen like a movie playing or web page with animations.
  3. Audio through the onboard headphone jack keeps playing even when the sound and audio through the graphics card shuts off. The computer is still running, just not the graphics card.
  4. MATE's power settings are set to never go to sleep.
  5. The monitor never does this by itself unless connected to this particular computer. Also, mouse movement awakens everything, so I doubt it's the monitor. I tried another monitor and had the same issue.

My thoughts
-bad HDMI cable?
-overheating?
-PCI-e being shut off for some reason?
-haven't found the right driver?

Specs:
Ubuntu Mate 18.04.2 LTS 32 bit
Kernel Linux 4.18.0-18-generic i686
Intel Dual Core E2160, 2GB RAM
Nvidia GT430 air cooled with 1GB DDR3 and HDMI out.
Yes, a POS antique, but dammit it's paid for, it was free in the first place, and it gets the job done nicely!

Note:
I am a NOOB. Please provide detailed instructions if I need to pull logs, etc. Thanks to anyone who can help!


#2

Install Caffeine. It sits in your system tray. When you want to play a movie, right click caffeine and select "disable screensaver".


#3

Issue solved!

Wonder why this functionality doesn't come by default? Does no one watch movies?