Question Flicker in new monitors at 144hz

[tlochner]

Question:
I have 2 144hz 4K(3840x2160) monitors both hdmi 2.1, with 15 ft cables tied to 1 Nvidia 3070ti graphics card.
With 15ft cables I get random flickers, maybe losing gsync???
On display port 1.4 at 155hz everything is fine with 15ft cables.
With 6ft hdmi cables at 144hz things seem better, not sure yet if flicker is still there.

The cables are 8K cables, the best I can find. I've tried 3 sets of cables, 2 sets of monitors, and two graphics cards, ASUS TUF Gaming with dual Hdmi outputs.

Is 15ft hdmi cables at 4K 144hz, dual monitors an issue????
Nvidia and Asus are NOT saying it is. Your thoughts, please.

 

[Fix_that_Glitch]

HDMI signal doesn't degrade until about fifty feet. Hdmi sends 0-1's so it is not the same as an electrical resistance like say a vga cord. Are the hdmi cables 2.1?

 

[tlochner]

Yes they are 2.1.
Does the Video card need more power, in its output, to drive 2 monitors at 4k 144hz simultaneously?
Where do you think the problem lies?
Tried 3 sets of 15ft cables. 6ft cables seem to be OK. 15ft DP cables are OK.

I think it's in the video card being able to drive 2 monitors 15ft on Hdmi.

Thoughts?
Thanks for your input.

 

[sizzling]

I’d take a look at this, it is similar to what I have seen elsewhere and my own experience.

https://www.tomshardware.com/news/hdmi-2-1-cables-are-about-to-get-longer-a-lot-longer

I had issues connecting my 3080 to a 4K 120Hz TV. Only after giving up on cheaper cable did a short more expensive and allegedly high quality cable did all the problems go away. I’d never had issues with any HDMI until I was in a situation requiring full 2.1 bandwidth. It does seem 2.1 is really fussy.

 

[tlochner]

Yep, I think its the cables and I think the SPEC should consider 4k 144hz and cable distance.
However, I'm not paying $60 each for 2 cables, active fiber optic cables, to see if that solves it.
If it was 30ft ok, and it was 1 cable needed, I would.
This is suppose to be in SPEC.

For now I'll stick with display port 4K, 155hz, dual monitors, and no known issues.
Those cables cost $25 each.

I still think maybe the video card design can't power/drive 2 lines at that resolution/frequency.

Any other ideas?

 

[Glenwing]

"8K" and "2.1" are not actual HDMI cable ratings.

Are you using an Ultra High Speed HDMI cable, and does it have a certification label attached to either the cable or the packaging?

Please see here for information on identifying HDMI cables:
https://www.hdmi.org/spec21sub/ultrahighspeedcable

HDMI signal doesn't degrade until about fifty feet. Hdmi sends 0-1's so it is not the same as an electrical resistance like say a vga cord. Are the hdmi cables 2.1?

There is really no general rule for how long an HDMI cable can be before the signal cannot be decoded, as it depends highly on the signal speed, which is determined by the video format. Some HDMI cables may be able to pass High Speed certification at 50 ft, but there is no cable that will pass UHS certification at that length. 15 feet is already going to be quite challenging.

 

[Fix_that_Glitch]

"8K" and "2.1" are not actual HDMI cable ratings.

Are you using an Ultra High Speed HDMI cable, and does it have a certification label attached to either the cable or the packaging?

Please see here for information on identifying HDMI cables:
https://www.hdmi.org/spec21sub/ultrahighspeedcable



There is really no general rule for how long an HDMI cable can be before the signal cannot be decoded, as it depends highly on the signal speed, which is determined by the video format. Some HDMI cables may be able to pass High Speed certification at 50 ft, but there is no cable that will pass UHS certification at that length. 15 feet is already going to be quite challenging.

Like I said after 50 ft you should consider a a signal booster. It's pretty common knowledge. 15 feet shouldn't be a problem. He believes the flickering is being caused by the length of the cable, but it could be anything, like drivers, a bios update needed, fussy frequency from the monitors, the weight of the cable bending the hdmi port etc.

 

[tlochner]

for hdmi cables tried these all with others too ...

https://www.amazon.com/Cable-Stouch...285TZF/ref=psdc_3230976011_t3_B08KZNRSD3?th=1

https://www.amazon.com/dp/B08KZNRSD3?ref=ppx_yo2ov_dt_b_product_details&th=1

i guess 15ft is just is quite challenging. Cable distance should have been part of the spec.