[SOLVED] 1440p 144Hz over HDMI with 780m

[O-steal]

Hello

I have a ROG g750jh laptop equiped with a 780m. The available outputs are hdmi, vga and there is a thunderbolt on the system.

I read that technically, I should be able to get 144Hz 1440p using HDMI (2.0 supported) but I tried several cables and I cannot get more than 60Hz.

What is the issue here?

Would I be able to get it to run using a mini display-port to display-port cable?

Thanks

 

[dotas1]

Your gpu supports hdmi 1.4a though. 1440p@60Hz

 

[O-steal]

Your gpu supports hdmi 1.4a though. 1440p@60Hz

Thanks for the clarificaiotn, couldn't find the specs online. And according to you, I fI were to blug a mini display port in my thunderbolt, would the card be able to leverage it?

 

[dotas1]

I don't really know but I think not. Wait for someone else to verify it though.

 

[O-steal]

I tried using the mini display port to display port adapter from my rift S and I am able to reach 1440p 120Hz only, but the color changed form RGB 'full' dynamic range to YCbr422 'limited' dynamic range and texts (for example: the colored texts in 'display settings' are blurry and usually blue hyperlink alternate between purple and gray (as if colors were unaligned) depending on the word) and some icons (like tab miniatures in chrome) are blurry (exactly as if windows scaling was offset but scaling is to 100% and the option to automatically let windows fix apps is on 'off').

If I scale back to 85Hz, I get back RGB and full dynamic range and all icon scaling and text color is fixed. I thought I could reach 144Hz with displayport, but 120Hz is max here, and text/icons are broken. What would be the root cause?

 

[dotas1]

Your issue is that both DP and HDMI versions that are supported by your GPU, are not capable of 1440p/144hz.

 

[O-steal]

Your issue is that both DP and HDMI versions that are supported by your GPU, are not capable of 1440p/144hz.

Likely, but I was seeking hard evidence on that.

 

[dotas1]

Likely, but I was seeking hard evidence on that.

https://www.notebookcheck.net/NVIDIA-GeForce-GTX-780M.88993.0.html
Quoting from the link:
"The improved feature set now includes support for up to 4 active displays. Furthermore, high resolution monitors of up to 3840x2160 pixels can now be connected using DisplayPort 1.2 or HDMI 1.4a if available. "

So the supported versions are DP 1.2 and HDMI 1.4a.

 

[O-steal]

https://www.notebookcheck.net/NVIDIA-GeForce-GTX-780M.88993.0.html
Quoting from the link:
"The improved feature set now includes support for up to 4 active displays. Furthermore, high resolution monitors of up to 3840x2160 pixels can now be connected using DisplayPort 1.2 or HDMI 1.4a if available. "

So the supported versions are DP 1.2 and HDMI 1.4a.

That's the issue, DP 1.2 should support 144Hz 1440p but here it doesn't and 120Hz is only working by scaling down quality and going YCbr422

Maybe the mini display port adapter form Oculus is not 1.2? This would be strange

 

[dotas1]

The fact that it works in 85Hz makes me think that you have DP 1.1 which supports up to 1440p@85Hz. Maybe the manufacturer of the laptop, cheaped out on it and went with a 1.1 instead of 1.2

 

[O-steal]

I found the answer, in the details of the thunderbolt specs, you can see it is thunderbolt 1 with max 10Gbs so only DP 1.1

ROG G750JH - Support

www.asus.com