LG 48CX OLED - 4K 120 Hz

Has anyone had an issue with a white/black horizontal bar about 1 or 2 inches thick randomly flashes at the top of the screen 48" screen ?
Tried a couple of different hdmi cables but its still there and it doesn't appear on my 2nd monitor. Everything is updated to latest drivers

Edit managed to get a clip of it happens at 2 second mark
 
Last edited:
craigmmmm said:
Has anyone had an issue with a white/black horizontal bar about 1 or 2 inches thick randomly flashes at the top of the screen 48" screen ?
Tried a couple of different hdmi cables but its still there and it doesn't appear on my 2nd monitor. Everything is updated to latest drivers

Edit managed to get a clip of it happens at 2 second mark
Click to expand...

Does it do it using the TV apps? Or just when using pc
 
Looks like an panel failure to me, more so if its occurring on apps, different hdmi ports and devices ie sky, cable or xbox etc.

When you contact retailer or LG, just tell them you reset the TV to factory settings, tried several hdmi cables, different power plug in another socket and latest firmware installed and its still flashing like that everywhere as in all hdmi ports, apps etc. < This should avoid you having to do any other diagnostic and they can fast track to a repair, takes the repairers 30-45 mins to swap the panel out for a new one.
 
Have tested with PS5 and using Prime via the apps and Monitor was ok no issues so Panel seems to be ok ??
I have used the following HDMI leads (From the Rainforest) in the tests and all present the issue when using the PC but nothing else.
I Have tested the Leads with a LG 38GL950 38" 3840x1600 NANO IPS 144Hz 1ms G-Sync no issues but can only run at 60hz.

So are the hdmi leads not up to running the cx48 or is it the panel or GPU which is a 3090 ??
didnt have the issue until recently and the cx48 has run fine on the Maxonar in the past

Thanks for any advice given

8K HDMI 2.1 Cable 2m(6.6Ft),Maxonar (Certified) Ultra HD 48Gbps High Speed 8K60 4K120 eARC RTX 3090 HDR10 4:4:4 HDCP 2.2&2.3 Dolby Compatible with PS5,Xbox Series X,Roku/Fire/Sony/LG TV

4K DisplayPort Cable, JSAUX 3M DP Cable (4K@60Hz,2K@144Hz,2K@165Hz,3D) High Refresh DisplayPort to DisplayPort Lead Nylon Braided Compatible for Gaming Monitor, HDTV, Display, PC/Laptop, etc - Grey

JSAUX 2.1 HDMI Cable 8K 3m Ultra HD Cable High-Speed Lead 48Gbps, HDMI Cable (8K@60Hz 7680x4320, 4K@120Hz) Supports eARC HDR10 HDCP 2.2 & 2.3 DTS:X 3D CEC, Compatible with PS5 PS4 PS3 X-BOX QLED TV



 
Last edited:
craigmmmm said:
Have tested with PS5 and using Prime via the apps and Monitor was ok no issues so Panel seems to be ok ??
I have used the following HDMI leads (From the Rainforest) in the tests and all present the issue when using the PC but nothing else.
I Have tested the Leads with a LG 38GL950 38" 3840x1600 NANO IPS 144Hz 1ms G-Sync no issues but can only run at 60hz.

So are the hdmi leads not up to running the cx48 or is it the panel or GPU which is a 3090 ??
didnt have the issue until recently and the cx48 has run fine on the Maxonar in the past

Thanks for any advice given

8K HDMI 2.1 Cable 2m(6.6Ft),Maxonar (Certified) Ultra HD 48Gbps High Speed 8K60 4K120 eARC RTX 3090 HDR10 4:4:4 HDCP 2.2&2.3 Dolby Compatible with PS5,Xbox Series X,Roku/Fire/Sony/LG TV

4K DisplayPort Cable, JSAUX 3M DP Cable (4K@60Hz,2K@144Hz,2K@165Hz,3D) High Refresh DisplayPort to DisplayPort Lead Nylon Braided Compatible for Gaming Monitor, HDTV, Display, PC/Laptop, etc - Grey



JSAUX 2.1 HDMI Cable 8K 3m Ultra HD Cable High-Speed Lead 48Gbps, HDMI Cable (8K@60Hz 7680x4320, 4K@120Hz) Supports eARC HDR10 HDCP 2.2 & 2.3 DTS:X 3D CEC, Compatible with PS5 PS4 PS3 X-BOX QLED TV
Click to expand...

Ok, if its defiantly not occurring on inbuilt apps or normal freeview/sky/cable tv and just the PC connection, have you tried to switch the PC hdmi connection to an different hdmi port, say hdmi port 3 or port 1 etc ?

Id try that and see how it goes and maybe try again with an different hdmi cable, you can edit or set up the hdmi to be PC input also.

Its always worth factory resetting the TV also just in case something has got messed up with the settings, do this before you do any testing might be worth noting down your brightness, contrast setting values on paper.

Issues like the one you are having its like a trial and error thing, where you have to slowly test one thing at a time to figure out that needle in a haystack or what is perhaps triggering the issue.

If its still occurring, the easiest test would be to try a different GPU if you can, or reduce the PC settings temporary ie go back to 4K and 60hertz and 8 bit RGB like the lowest Nvidia display settings, and then see how it goes really.
 
Last edited:
R3X said:
Ok, if its defiantly not occurring on inbuilt apps or normal freeview/sky/cable tv and just the PC connection, have you tried to switch the PC hdmi connection to an different hdmi port, say hdmi port 3 or port 1 etc ?

Id try that and see how it goes and maybe try again with an different hdmi cable, you can edit or set up the hdmi to be PC input also.

Its always worth factory resetting the TV also just in case something has got messed up with the settings, do this before you do any testing might be worth noting down your brightness, contrast setting values on paper.

Issues like the one you are having its like a trial and error thing, where you have to slowly test one thing at a time to figure out that pin in the needle or what is perhaps triggering the issue.

If its still occurring, the easiest test would be to try a different GPU if you can, or reduce the PC settings temporary ie go back to 4K and 60hertz and 8 bit RGB like the lowest Nvidia display settings, and then see how it goes really.
Click to expand...

Thank for the advice I will try that and give it a go
 
Big fan of Ibra cables here, I once wasted £60 quid on other branded hdmi cables claiming they were 60hertz and 4K hdr compatible which all failed, first Ibra cable I got worked out the box, got the ibra orange and now Ibra fiber optic hdmi cable, hoping the fiber optic cable goes out of its specs and does 120hertz, RGB 10bit for me next year.
 
I've not had any trouble with the Ugreen branded cables, happily running 4k120 over a 2 m cable. Admittedly, the shorter length could be helping them out but my other cables from them have always been reliable.
 
craigmmmm said:
Has anyone had an issue with a white/black horizontal bar about 1 or 2 inches thick randomly flashes at the top of the screen 48" screen ?
Tried a couple of different hdmi cables but its still there and it doesn't appear on my 2nd monitor. Everything is updated to latest drivers

Edit managed to get a clip of it happens at 2 second mark
Click to expand...
did you try different hdmi port on GPU. Im having very sporadic similar flashes and when i plug cable to second hdmi GPU port flashes are gone. Cable is certified
 
^ Not all GPUs have more than one HDMI port. Crazy really.

I've just ordered a DP1.4 to HDMI2.1 adapter from the USA. Taking ages to arrive (weeks), and wasn't cheap at around £40 but seems it's the only one which can actually do 4k120. Could be an option if it is the port playing up.
 
SilverCider said:
I've not had any trouble with the Ugreen branded cables, happily running 4k120 over a 2 m cable. Admittedly, the shorter length could be helping them out but my other cables from them have always been reliable.
Click to expand...

ugreen are pretty decent, never had issues with them either, you are right though the shorter the cable the easier it tends to work. I still have a 1 metre hdmi cable from the poundland for 99p which hit 4K, 60hertz, HDR no sweat which the £20-30 other rainforest hdmi so called 4K hdr cables failed, but they were 5 metres+.

Hdmi Certification is hit and miss also, does not mean its guaranteed to work, still trial and error sadly.
 
TheOracle said:
^ Not all GPUs have more than one HDMI port. Crazy really.

I've just ordered a DP1.4 to HDMI2.1 adapter from the USA. Taking ages to arrive (weeks), and wasn't cheap at around £40 but seems it's the only one which can actually do 4k120. Could be an option if it is the port playing up.
Click to expand...

Do you have a link for that adaptor please, sounds pretty handy perhaps in the future.
 
TheOracle said:
^ Not all GPUs have more than one HDMI port. Crazy really.

I've just ordered a DP1.4 to HDMI2.1 adapter from the USA. Taking ages to arrive (weeks), and wasn't cheap at around £40 but seems it's the only one which can actually do 4k120. Could be an option if it is the port playing up.
Click to expand...
R3X said:
Do you have a link for that adaptor please, sounds pretty handy perhaps in the future.
Click to expand...
In future I'd expect graphics cards to have DisplayPort 2.0 which carries HDMI 2.1. Right now cards only have DP1.4 which can be passively adapted to HDMI 2.0 with a cable.
 
Ico said:
did you try different hdmi port on GPU. Im having very sporadic similar flashes and when i plug cable to second hdmi GPU port flashes are gone. Cable is certified
Click to expand...

Only got one HDMI port on the card unfortunately but on checking today the cable seems to move about a lot in the HDMI port on the GPU and isn't as solid as the TV port which is a firm connection .
 
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