PC Drivers & Software

[overproof876]

LG 43UJ6200 TV

Power Colour RX480 8GB

Radeon Software Version: 19.4.1

CPU: Xeon X5675 O.C to 4.2 Ghz

HDMI 2.0 Cable 6ft (no adapters)

Microsoft Windows 10 Professional (x64) Build 17763.437 (1809/RS5)

Disabling HDMI Link assurance seems to get rid of the video distortion i was seeing with HDR enabled & a pixel rate above 4:2:0 & Color Depth above 8bpc. I still can't get 60Hz though, it always drops to 30Hz when I go above those settings.

Also, Windows allows me to set 59Hz or 60Hz but when I check AMD settings it goes back to 30 Hz for some reason.

[detrophy]

The RX480 has an HDMI 2.0 interface with a bandwith of 18GBit/s wich is not enough to drive 4k @ 60Hz @ HDR(>=10bit/channel) @ 4:4:4.

Reduce the chroma subsampling to 4:2:2 or 4:2:0.

Regarding your disortions:

Do you use a really long cable?

Is it a high quality cable?

The longer the cable, the better the quality should be, or you will see distortions (like weird colored bars or blackouts). I´ve got these distortions too while I was unsing my RX580. With the R VII, these problems are gone.

[overproof876]

The RX480 uses HDMI 2.0b

https://www.amd.com/en/products/graphics/radeon-rx-480

[detrophy]

These are just extensions to allow for (2.0a) HDR with static metadata and (2.0b)HybridLogGamma(HLG) HDR. They do not raise the bandwith available for transmission of video data.

[overproof876]

2.0b supports 4k 60Hz according this & other sources:

https://www.cnet.com/how-to/what-is-hdmi-2-0b/

[detrophy · Accepted solution]

CNET is using a confusing chart here. Yes, HDMI 2.0b is capable of 4k with 60hz and 10/12bit HDR, but only with 4:2:2 or 4:2:0 chroma subsampling. If you want 4:4:4, you will need to use a lower refresh rate, like 30hz.

This is due to bandwith limitations of HDMI 2.0 a/b, wich has a peak bandwith of 18Gbit/s for video and audio. See the handy charts here.

[overproof876]

Thanks for the clear & detailed explanation. I will attempt to use the settings from Acoustic Frontiers' charts & share my results.

Also, Acoustic Frontiers seems quite impressive, thanks for putting me on to them.

The full article for anyone interested:

http://www.acousticfrontiers.com/uhd-101-v2/

[overproof876]

UPDATE

I changed cards to a MSI Armour RX580 & bought a Toptrend 4k HDMI cable off Amazon.

https://www.amazon.ca/gp/product/B01HFFCDU2/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

I was able to get 4:4:4 (Full RGB) @ 12bpc & 30Hz with no artifacting.

I was able to get the 60Hz with 4:2:2 @ 8pc also with no artifacting.

I will try the RX480 again @ a later date to see if it was just the cable that made the difference.

[overproof876]

I was able to achieve the same with the RX480, 4:4:4 (Full RGB) @ 12bpc & 30Hz with no artifacting.

Even though I was not able to achieve the desired 60Hz at least I was able to identify that the cable was causing the artifacting & instability i was experiencing.

[detrophy]

What’s the monitor you’re using with these settings?

[overproof876]

i'm using the same LG 43UJ6200 TV