On Sun, Apr 4, 2021 at 10:26 AM D. Hugh Redelmeier via talk <talk@gtalug.org> wrote:
> | From: Evan Leibovitch via talk <talk@gtalug.org> > > Thanks for the more complete information. > > What the exact brand and model of your Radeon RX 550? Are you sure > that the HDMI port conforms to HDMI 2.x? > > Remember that I'm not an expert. > > Jose Dias' experiment seems worthwhile. > > | The left (HDMI) screen will (randomly to me) do one of a few things: > | > | 1. Go off (the monitor reports lost signal) and back on after about > 1-2 > | seconds. > | > | 2. Go off (no signal) for 3-4 seconds and then back on, briefly to > flat > | green or static and then normal. > > I would perhaps call that briefly blanking out. There is probably an > accepted term for this but I don't of know one. > Screen blanking is a feature of dpms, could try turning it off for the monitor. > I doubt that that symptom has anything to do with the compute power of > the GPU. It "feels" more like the monitor has been unhappy with > something about the signal itself. > I ran into similar problems with a dual monitor setting up IOMMU / Vt-d on intel. Blanking the primary boot screen and no display on the other on boot up. > Some video cards have fewer clocks than outputs. Some outputs were > required to share clocks. This could cause mysterious problems. I > have no idea if that is the case here. > > Are you sure that HDMI is driving your left monitor at UltraHD > resolution at 60Hz? > > | I've tried different cables, no difference. > > That would have been my first suggestion. I once had a mysterious > problem fixed by a new HDMI cable. HDMI is complicated and made more > so by papering over the complexity. As HDMI bandwiths increase, more > marginal cables fail. > > Are any problems logged by the system about the time of these events? > (The few times that I've tried to understand a Windows log have been > very unpleasant and not at all useful.) > > Experiment: shut down the system, disconnect the right screen, and > reboot. Does it flicker? > > Experiment: switch to mirroring (where each display shows the same > thing). Does it flicker? > > Experiment: try running both monitors at a slower refresh rate. > Does it flicker? > > Experiments: try running the monitors at a different refresh rates (if > that's possible). Left slower than right. Also left faster than > right. > > Experiments: try the same set of experiments, this time varying the > resolution rather than the refresh rate. > --- > Post to this mailing list talk@gtalug.org > Unsubscribe from this mailing list > https://gtalug.org/mailman/listinfo/talk > -- Russell
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