Question Graphical artifacts with only one input/source

[Pedeadstrian]

Hello all, got a weird situation here. I have a PC, TV, and numerous cables that can each interact with each other and other devices just fine, but whenever I am specifically trying to connect my PC to my TV via HDMI (the only port my TV has) I get graphical artefacts. It doesn't matter what TV port or what cable I use. I can connect my PC to my monitor with the same cable and PC port and can connect my TV to my laptop and game systems with the same cable and every TV port.

TV: Bravia XR A80J (to quote the site: "Features specified in HDMI2.1 4K120")
Cables: Numerous (but one trying to set up on is ~5m, 48Gbps)
Important PC Specs from DXDiag:

Spoiler

Operating System: Windows 10 Pro 64-bit (10.0, Build 19044) (19041.vb_release.191206-1406)
System Manufacturer: Micro-Star International Co., Ltd.
System Model: MS-7C79
BIOS: 1.60 (type: UEFI)
Processor: Intel(R) Core(TM) i7-10700K CPU @ 3.80GHz (16 CPUs), ~3.8GHz
Memory: 32768MB RAM
Available OS Memory: 32688MB RAM
Page File: 8730MB used, 28821MB available
DirectX Version: DirectX 12

Card name: NVIDIA GeForce RTX 3080 Ti
Display Memory: 28452 MB
Dedicated Memory: 12108 MB
Shared Memory: 16344 MB
Current Mode: 2560 x 1440 (32 bit) (240Hz)
HDR Support: Supported
Driver Version: 31.0.15.1659

TL;DR specs: more than capable of 4k120Hz

I have tried doing a clean install of my drivers, messed with all sorts of graphics options in Nvidia Control Panel, prayed to the dark lord C'thulhu, etc. I just want to play pixel games on my 65" TV. Any help you could provide would be greatly appreciated, and sorry in advance if I left out pertinent info. I have attached an image of what I am referring to, and something of interest to note: that's an image that was grabbed from my laptop while testing but taken while it was connected to my PC. The image flickers so it's not like the display is frozen but somehow it retained the image even after restarting the PC and the TV. Before I tested my laptop the image was purely artefacts. This image was generated by connecting my laptop to the TV (which worked just fine) and the swapping the cable to the PC.

 

[kerberos_20]

do you have another hdmi 2.1 capable device?

 

[rocktalkrock]

Have you tried booting to the CPU's onboard graphics to see if the same artifacts still appear?

 

[Pedeadstrian]

do you have another hdmi 2.1 capable device?

Not to my knowledge but with trying multiple resolutions, refresh rates, and cables I don't think that's a problem.

Have you tried booting to the CPU's onboard graphics to see if the same artifacts still appear?

So, here's the weird thing. I just tried the HDMI port on my mobo (which I have been conditioned to forget about) and that worked. Then I randomly decided to try the HDMI port on my GPU again, outside IGD mode, and after fiddling with a few settings I got it to work without issue. It was in Duplicate mode at 1080p@60Hz. I then lowered to 30Hz with artefacts and returned it to 60Hz with artefacts. Even though it was the same exact settings it didn't work. I am going to continue fiddling and hope I just get lucky again, but if what I've just mentioned brings out any ideas I'd love to hear them.