120Hz 1080p over HDMI seamlessly?

[Laurijan]

Hi!

I got a 55SJ810V LG TV as monitor that accepts 120Hz as input when using 1080p.
Now i have the problem with 120Hz that with every cable i tested even a HDMI premium certified one i get shot black screens as like the signal is lost for a moment.
This happens normaly when starting up the PC after it goes to desktop and then every 25min or so browsing.
When i am scolling in facebook it happens most often.

With the HDMI bandwidth calculator i dont get near 18Gbit/s that my cables should support, only like 10Gbit when using 1080p 120Hz 8bit RGB so i dont think its a bandwidth problem.

TV firmware is up to date.

With 2160p 60Hz i got no problems.

Any idea why?

 

[Papahyooie]

I have a 144hz monitor that won't do anything above 60hz 1080p on the HDMI ports. I have to use DL-DVI. I always just assumed it didn't have enough bandwidth. It could be that your cable supports that much bandwidth, but the hardware in the TV does not actually support what it says it does. You'd have to do some digging on the detailed specs of the TV to know for sure.

 

[toilet pepper]

Hi!

I got a 55SJ810V LG TV as monitor that accepts 120Hz as input when using 1080p.
Now i have the problem with 120Hz that with every cable i tested even a HDMI premium certified one i get shot black screens as like the signal is lost for a moment.
This happens normaly when starting up the PC after it goes to desktop and then every 25min or so browsing.
When i am scolling in facebook it happens most often.

With the HDMI bandwidth calculator i dont get near 18Gbit/s that my cables should support, only like 10Gbit when using 1080p 120Hz 8bit RGB so i dont think its a bandwidth problem.

TV firmware is up to date.

With 2160p 60Hz i got no problems.

Any idea why?

It might be that the TV just emulates 120hz and not a true 120hz panel.

 

[Laurijan]

It might be that the TV just emulates 120hz and not a true 120hz panel.

I can choose 120Hz from windows so i think its a 120Hz panel

 

[Laurijan]

Now i use a HDMI cable from an IPTV box and the 120Hz works nicely. After coldstart yesterday i had a short black screen when it went to desktop but after that no interuptions.
The IPTV box cable is quite thick compared to the other cables that i have but seems also much cheaper.

 

[RejZoR]

I think you need HDMI 2.0 connectivity and cable to get such high refresh rates.

 

[Laurijan]

I think you need HDMI 2.0 connectivity and cable to get such high refresh rates.

GTX1080 has HDMI2.0b and TV too 4 ports but there are no hdmi 1.4, 2.0, 2.0a, 2.0b cables only High Speed cables with and without ethernet and Standart Speed cables with and without ethernet.
Really only the build quality of my High Speed cable defines how much Gbit/s you can drive thru - wire gauge and insulation for example. Edit: and length seems to matter

 

[Vya Domus]

Use a very short cable.

 

[Laurijan]

Use a very short cable.

The one i have least problems with is only 1.5m and very thick.
Edit: Best cable so far is one with ferrite cores on both ends even though its 2m it works like a charm.

 

[Aquinus]

I think you need HDMI 2.0 connectivity and cable to get such high refresh rates.

1080p @ 120Hz only requires HDMI 1.3 or later. 1440p @ 120Hz requires 2.0a.

My LG is "120Hz Tru-Motion" or whatever they call it. It's just a fancy way for saying that it does the math to fill in the blank frames. I haven't tried plugging my machine into it and seeing if I could fiddle with refresh rates since I usually just want to run at 4k if I do.

 

[Jetster]

or display port

 

[Aquinus]

or display port

It's a TV.

 

[Laurijan]

1080p @ 120Hz only requires HDMI 1.3 or later. 1440p @ 120Hz requires 2.0a.

My LG is "120Hz Tru-Motion" or whatever they call it. It's just a fancy way for saying that it does the math to fill in the blank frames. I haven't tried plugging my machine into it and seeing if I could fiddle with refresh rates since I usually just want to run at 4k if I do.

With this TruMotion it is not possible to set 120Hz in Windows?

 

[qubit]

That sounds like an awkward problem you've got there and it seems to me like a software glitch somewhere. I've checked the HDMI specs of a GTX 1080 and your TV and confirmed that together they can support 1080p 120Hz over HDMI, so that's not the problem. This makes me wonder, have you got the latest video driver installed and the latest Windows patches? I suspect your do, so perhaps remove that driver and reinstall it and see if that fixes it.

You could also try turning off hardware acceleration in the browser. Another thing to try is to change the power management mode in the NVIDIA driver from adaptive to max performance and see if it helps. Perhaps creating a custom 1080p/120 mode will fix it. I'm pretty sure this problem is being caused by software bugs somewhere.

Finally, it's unfortunately possible that there's faulty hardware too, the TV or graphics card, with the nod going to the card imo.

GTX1080 has HDMI2.0b and TV too 4 ports but there are no hdmi 1.4, 2.0, 2.0a, 2.0b cables only High Speed cables with and without ethernet and Standart Speed cables with and without ethernet.
Really only the build quality of my High Speed cable defines how much Gbit/s you can drive thru - wire gauge and insulation for example. Edit: and length seems to matter

Correct on the HDMI cables. So many people get confused over this, especially when they've listened to shop floor salesmen who'll BS them about the different types of cable eg trying to sell a "4K HDMI cable" (at a premium price, of course) when there's no such thing, only high speed. They don't have to be expensive either, of course.

 

[Laurijan]

I use the newest nvidia driver that doesnt break HDR in windows.
It was the cable. I now use a 12e 2m cable with ferrite core on both ends thats not even very thick and get no signal interruptions with 120Hz.
Strange thing is that the more expensiv cables even a HDMI premium certified wont work as nicely as the ferrite core one that was cheap.

 

[FordGT90Concept]

http://www.lg.com/uk/tvs/lg-55SJ810V
Makes no mention of 120 Hz.

And yeah, HDMI is a crappy standard. Rather, it says nothing about cable/SNR over *any* length. If DisplayPort is an option, use it. Hell, even dual-link DVI will get more reliable results at this bandwidth.

 

[Laurijan]

So i gave up on 120Hz over HMDI, at least for desktop use but in games i might do it still. I tried like 5-6 cables and all give me lost signal problems. With 4K 60Hz 12bit i have no problem even though bandwidth is higher than 1080p 120Hz

 

[lyndonguitar]

http://www.lg.com/uk/tvs/lg-55SJ810V
Makes no mention of 120 Hz.

And yeah, HDMI is a crappy standard. Rather, it says nothing about cable/SNR over *any* length. If DisplayPort is an option, use it. Hell, even dual-link DVI will get more reliable results at this bandwidth.

http://www.lg.com/us/tvs/lg-55SJ8500-4k-uhd-tv mentions TruMotion 240 which translates to 120Hz. But slightly different model
https://www.displayspecifications.com/en/model/ae48ae4 this one shows 120hz though

Have you tried messing with the TV settings(not windows or gpu). sometimes there is a hidden setting there which might fix the problem(like activating TruMotion, or changing color settings, or turning off noise reduction features)

 

[Laurijan]

Here it says in the online manual that my TV support 1080p 120Hz to PC
http://kr.eguide.lgappstv.com/manua...w35__etc__resolutionhdmidtv_e_c_a_t__eng.html