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Suspending & Waking up
- I had an issue with a ViewSonic monitor connected to an HDMI matrix where the display would not wake up after sleep. I had to turn off and on the monitor to get the display back. It was fixed completely by turning off in the monitor's settings the option "Auto-Detect".
- On modern hardware there seems to be many options to remove screen tearing entirely:
- HDMI starting with version 2.1 has an extension called VRR (Variable Refresh Rate) that seems to take care of the problem. But this requires both an HDMI 2.1 capable monitor and an HDMI video card (only very recent nvidia cards from 2020 have that).
- AMD has FreeSync but it requires an AMD card (Radeon).
- Nvidia has G-sync but is quite useless as it needs a monitor supporting G-sync. Almost no monitor does because G-sync require a special hardware module, whereas they all support FreeSync since FreeSync is free.
- Nvidia finally started supporting FreeSync on most monitors but it requires a DisplayPort cable since in fact it uses a DisplayPort technology for VRR (whereas AMD cards can do it over HDMI, even without HDMI 2.1). Nvidia probably won't add support for FreeSync over HDMI 2.0 and lower (see for instance https://www.nvidia.com/en-us/geforce/forums/discover/292013/freesync-with-hdmi/).
- For HDMI TVs, no solution except HDMI 2.1.
- If you cannot use a hardware solution (mostly it means using an nvidia card connected to a monitor by HDMI), you have to resort to software Vertical Sync. See for instance this article for screen tearing / vertical sync on KDE.
Testing Screen Tearing
- This is a good URL for checking screen tearing in Chromium: https://www.youtube.com/watch?v=DaBQ3hCJxpE.
- Moving around windows very quickly is also an efficient way of testing tearing on the desktop environment.
- There are also downloadable movies for checking movie players (available for instance at http://silverlinux.blogspot.com/2013/05/vsync-test-videos.html).
- With long HDMI cables (~8 meters), it can be impossible to have a 4k signal at 60Hz transmitted correctly (I had pixel artefacts all over the picture). You really need a premium, high quality recent cable for such purposes (usually these cables are optical or active cables and cost much more). They are also directional and not bi-directional.
- Note that long cables cannot be certified with an official HDMI certification (such as Ultra High Speed, with 48 Gbps bandwidth). The official HDMI certification stops at around 3 meters. Thus you have to find a vendor at random that does provide such cables with a high enough bandwidth, so that they work correctly.