Image has fine blue/grey lines on 4K TV

[Yanta]

Firstly, best wishes to all for the holiday season.

I've recently purchased a LG 55UH950T 4K UHD 3D TV. It supports HDR, HDMI 2.0a and ARC.
My PC has a GTX 950 OC with 2gb GDDR5. The cable is a 3m HDMI 2.0 cable.
Audio gets to my blu-ray player via optical cable from the TV to the Blu-ray player
As soon as I turned it on it detected the 4K TV and switched to 4K resolution. Too easy!

But... There are fine blueish-grey lines. Most noticeable on white areas of the screen. This happens just at the windows desktop, and when running programs like PotPlayer. So, it's not the MKV files. (Which are typically straight backup from my original Blu-ray disk - No compression/Re-encoding).

I've tried 30hz up to 60hz. Same thing.

Any ideas what might be causing this?

thank you

[hello_hello]

Got to ask.... are the lines still there when using another input device or watching free to air TV etc? If so, it's probably a problem with the screen.

[Yanta]

tbh, I haven't watched free to air TV since the early nineties, and the tv isn't even connected to an aerial nor do I have one.
Playing a 1080p Blu-ray disk, (equals - because it has lots of whites), no, these fine lines do not appear to be present