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CAC-1080 Not able to get 60hz at 4k using Geforce 1080 or Intel 630

Updated on 28-01-2021 in Adapters and Cables
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5 on 25-01-2021

I have a Sony TV that is a few years old now, it only has HDMI ports but they can do 4K60hz. Attached to the TVI have a HTPC with a Intel HD 630 graphics card.

I purchased the CAC-1080 to be able to connect the htpc to the TV at 4K60 (3840×2160 60Hz), which is only supported by the DP-outlet on the HTPC. I’ve verified that the DP outlet can do 4K60 by connecting it to another screen (DP-DP).

When connecting the HTPC using the CAC-1080 to the TV i am only able to get 4K30. At 60hz the TV is just blank.

I then connected the same HDMI cable to the HDMI port of a Geforce 1080, it was able to do 4K60, so it is not a problem with the TV port or the HDMI cable.

I then try to connect the CAC-1080 to the DP port of the Geforce 1080 and using the same HDMI-cable and port on the TV. Now i can only do 4K30 again. (falls back to 30hz instead of 60hz)

So it seems the CAC-1080 is preventing me from getting 4K at 60hz, which is the only reason i bought it.

What can i do? Will a firmware upgrade of the CAC-1080 help? I have the latest graphics drivers on both PCs.

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Baak 0 on 27-01-2021

Hi Mariux,

What TV are you using? model + modelnumber.

Have you updated the firmware on the 1080? for DisplayPort?

https://www.nvidia.com/en-us/drivers/nv-uefi-update-x64/

There is no firmware update for the CAC-1080.

But it still reads like as if you are using a HDMI 1.4 cable instead of 2.0. Yes 1.4 can do 4K60Hz. But I think you need the HDMI 2.0 for the adapter to work

 

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joevt 0 on 27-01-2021

4K 60Hz over HDMI requires 8bpc RGB or 444. HDMI 2.0 pixel clock for 4K 60Hz is 594 MHz.

You can do 10bpc if 422 or 420 is used. I don’t think Intel 630 can do 420 but it can do 422 and the CAC-1080 says it can convert RGB or 422 to 420.

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mariux 0 on 27-01-2021

The TV is a Sony KD-55X8505B

I don’t think i have updated the firmware for the Geforce 1080, but it can do 4k60hz using display port when connected to my ASUS monitor. My HTPC can also deliver 4k60hz when connected to this monitor using DP.

So:
(1) Geforce1080PC -> DP -> AsusMonitor = 4k60hz
(2) Geforce1080PC -> HDMI -> SonyTV= 4k60hz
(3) HTPC -> DP -> AsusMonitor = 4k60hz
(4) HTPC -> CAC1080 (DP to HDMI) -> SonyTV= Doesn’t work with 4k60hz, can only do 4k30hz.

So there is no doubt the HTPC DP outlet can do 4k60Hz (As per 3), the HDMI cable can do 4k60hz (as per 2) and the SonyTV can do 4k60hz (as per 2). The only extra component in (4) is the CAC1080..

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mariux 1 on 27-01-2021

So i connected the Geforce with the SonyTV using the HDMI cable in question and it only wants to do 4:2:0 when running at 4k60hz

Does that mean the cable is 1.4? I checked the specs for the TV and all four HDMI ports are 2.0

joevt on 28-01-2021

The cable is probably fine.

Maybe the TV doesn’t support 8bpc 4:4:4? So you have to do 10bpc 4:2:2 or 4:2:0. Maybe it can do the other modes but you need to change a setting on the TV or override the EDID with an app like CRU?

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