Display blinking when connected to PC via USB-C to HDMI 2.1

Smilingly5 · February 16

I am using a PC connected to my Samsung S90D TV via a USB-C to HDMI 2.1 cable. It works fine right when the cable is plugged in or right when the computer turns on, but if I turn off the TV, wait a few minutes, and turn the TV back on, the video output starts blinking randomly. The issue is resolved when I reseat the cable or reboot the computer. This happens with 3 separate PCs - one running windows 11, one fedora, and one bazzite, so I don't think the PCs are at fault. The issue does not happen when plugging a hdmi cable directly into the hdmi port of my mini pc. It only happens when I use this usb c to hdmi 2.1 cable.

Not sure if related, but with the same cable, I've also been occasionally having an issue where it won't pass any audio to the TV. Sometimes rebooting the PC fixes this, but sometimes not.

I do not believe there is anything wrong with the cable because I tried plugging my computer into a 4k monitor I have (MSI MPG321URX) with the same cable, and was unable to reproduce the blinking issue.

Is there any setting I can change on the TV that will fix this? I tried updating it, which didn't help. I tried lowering the resolution from 4k120hz to 4k60hz, which also didn't help. The built in hdmi-self diagnosis test didn't find anything either. I'm using game mode and the input is set to PC.

Also, just to clarify, the reason that I want to use this cable specifically is because the hdmi port built into my mini pc (minisforum UN1265) maxes out at 4k60hz, while the USB C port can do 4k120hz.

kirashi · February 16

22 minutes ago, Smilingly5 said:

I am using a PC connected to my Samsung S90D TV via a USB-C to HDMI 2.1 cable. It works fine right when the cable is plugged in or right when the computer turns on, but if I turn off the TV, wait a few minutes, and turn the TV back on, the video output starts blinking randomly. The issue is resolved when I reseat the cable or reboot the computer. This happens with 3 separate PCs - one running windows 11, one fedora, and one bazzite, so I don't think the PCs are at fault. The issue does not happen when plugging a hdmi cable directly into the hdmi port of my mini pc. It only happens when I use this usb c to hdmi 2.1 cable.

Not sure if related, but with the same cable, I've also been occasionally having an issue where it won't pass any audio to the TV. Sometimes rebooting the PC fixes this, but sometimes not.

I do not believe there is anything wrong with the cable because I tried plugging my computer into a 4k monitor I have (MSI MPG321URX) with the same cable, and was unable to reproduce the blinking issue.

Is there any setting I can change on the TV that will fix this? I tried updating it, which didn't help. I tried lowering the resolution from 4k120hz to 4k60hz, which also didn't help. The built in hdmi-self diagnosis test didn't find anything either. I'm using game mode and the input is set to PC.

Also, just to clarify, the reason that I want to use this cable specifically is because the hdmi port built into my mini pc (minisforum UN1265) maxes out at 4k60hz, while the USB C port can do 4k120hz.

Sounds like a weird intermittent incompatibility with how the TV is processing the signal when using a USB-C to HDMI cable. You could verify this theory by using a completely different USB-C to HDMI cable - if it happens with one from another brand, it's likely the TV not liking USB-C Alt Mode video output, at which point you could contact the manufacturer for advice with their product.

That said, since you say it works fine with HDMI... it's unlikely that the TV manufacturer is going to help resolve something that only happens in very limited circumstances - they'll likely tell you to use HDMI since that works fine. Your Minisforum UN1265 also has DisplayPort 1.4 which might let you achieve 4K120Hz using a compatible adapter. It does seem that TVs are picky about this though.

https://www.amazon.ca/Cable-Matters-102101-BLK-Computer-Adapter/dp/B08XFSLWQF