Samsung S95B not displaying at 120Hz

[Logun]

Hello,

 

This gets a bit confusing so I will do my best to be clear:

3080 Ti

8K optical HDMI cable

https://www.monoprice.com/product?p_id=38626

Samsung S95B

 

Computer does have two other monitors (unsure if that plays into this)

 

This is where we are starting. We can see the S95B is only set to 60Hz. I wish to select 120Hz

 

 

I select this resolution, I click apply I get the pop up count down box and I click Yes (keep changes)

 

The Resolution box blinks white and reappears at which point the original 4k x 2k resolution @ 60hz is selected and nothing has changed - the resolution I tried to select and apply is not set.

 

1) the S95B is set to Game Mode

2) The "External Device Manager" -> Input Signal Plus is selected (radio button is selected)

 

****

I did have this working last night - I do not know how I got it working. I played around for an hour shut it off in frustration, came back after a break and it all just worked. **HOWEVER** during game play the screen would intermittently go black for a second or two. I switched to a much older game and experienced the same issue, just less often.

 

I'm not sure what to do. Any trouble shooting steps I should take to rule other things out?

[BiotechBen]

It's a 2.1 cable correct? And both source and monitor are 2.1 compatible? 

Many tvs will say 120hz effective refresh rate and are actually 60hz but use frame interpolation to do "120hz"

[Logun]

yes the cable should be good - 8K compatible == 120hz @ 4K

 

and the 3080Ti is 2.1 as well as the S95B. The S95B is supposed to be able to hit 144Hz too based on HDTVTest  (Linus referred to this vid in one of his as well)

 

[Logun]

The above was done using port 4 on the TV. I attempted to use other ports and this is what happened:

 

plug in HDMI

TV detects new source and asks "Is this a PC" I hold "Down" on the remote to indicate source is a PC

TV displays PC as 4k x 2k 60 hz.

Under PC resolutions in Nvidia Control Panel (pictured in OP) the highest resolution available shown is only 2560 x 1600

I enable "Input Signal Plus" through the TV settings and additional resolutions appear.

I select 3840x 2160 120hz apply it and it sticks.

I turn GAME MODE on through the TV settings and the TV goes black

 

This behaviour is repeated on other ports.

 

As well this is why it's so hard to trouble shoot because the symptoms keep changing. I'm still not sure if it's the cable or the TV

 

TV is currently off and I will turn on again in a few minutes to see what happens after it's been at rest for a bit

[Logun]

From a fresh start the TV exhibits the same behaviour as in the last post.

 

I assume this is a cable issue?

[Logun]

Cable failure confirmed. Had to borrow another 8K cable from a local store, disconnect the PC, move it over to the tv to test with. Boom proper 4K @ 120hz (actually I had it up to 144hz without issue)

[Moshi20021]

@Logun did you get it to work with long cable? I have tried 3 15m hdmi 2.1 active cables (one cable matters certified). 
i have the same issue as you. 
i can get tv to display 4k@120hz 10bit rgb hdr. But when activating gamemode it looses connection. 

[Blandtastic]

FWIW I had a similar issue. Turning on Game Mode fixed it immediately. 

 

Hope this helps. 

[Logun]

Yes sorry I didn’t notice the comments here - a new proper cable worked as expected. I was lucky I was able to test other cables against the suspected faulty one