I have bought a HDMI (to USB-C) cable that supposedly supports 4k @ 60Hz via HDMI 2.0.

The cable is called Uni USB C to HDMI Cable (4K@60Hz) Space Grey. Amazon link

I do not get it to work at 4k60, I have tried with a Windows Laptop (Lenovo Yoga 720-13) which I am not sure supports 4k60, and a MacBook Pro 13 2020 which supports 4k60.

I have used a LG 27UD58P-B Display which supports 4k60 according to LG. Moreover I have been using this display for years with DisplayPort at 4k60.

Is there any way (maybe some commands or software) to find out whether this cable really supports HDMI 2.0 and/or 4k60?

So far I have tried to use cscreen on MacOS to list all the available modes of the display, and the highest available option supporting 60 hertz is 2560x1440. Is this a possible indication that the cable really does not support HDMI 2.0?

  • That is not a true HDMI cable, so all bets are off. The HDMI consortium only certifies HDMI male to HDMI male cables. No one certifies USB Type-C male to "HDMI" male cables, so it's hard to know what this manufacturer was thinking. – Spiff Jul 5 at 1:48
  • Thank you, I did not know this. Lots of comments say that they got it to work at 4k60, however I can't know for sure whether these are legit or fake. Do you know no other way for me to determine the capabilities of said cable? My main worry is that the problem is not with the cable, and me spending even more for a better cable will not solve my problem.. – charel-f Jul 5 at 10:24
  • You probably don't mean "HDMI (to USB-C)" but rather "USB-C to HDMI". – harrymc Jul 7 at 9:53
  • Yes thats possible, does this make a difference? – charel-f Jul 7 at 20:57

First, rule out monitor issues. With LG 4K monitors, usually you have to turn on settings like "HDMI Ultra HD Deep Color" to enable 60 hz support. Also, verify that the HDMI input you are using supports 4k 60hz--may need to check the user's guide for this. Either one of those could explain why DisplayPort works at 60 Hz but HDMI does not. If you have or can use another monitor that supports 4K that you can test the cable with, test with that. If you have or can use another HDMI cable that supports 4K 60 Hz, test with that and your monitor.

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The Amazon page clearly states that the cable supports resolutions of "up to 3840x2160 @ 60 Hz" ... and unfortunately, that's likely the best information you can get about it.

You can infer some more details - the page does also mention that this is technically a "USB-C DisplayPort Alt-Mode" to HDMI cable, which (paired with the size of the HDMI end) indicates that there is likely active circuitry in the cable to convert from DisplayPort to HDMI. This is in contrast to the relatively unsupported "USB-C HDMI Alt-Mode", that could be almost entirely passive.

product photo

As is always the case, both your computer and your display must support the modes you're trying to use. The LG 27UD58P-B certainly claims to support what you're after, and I would expect the MacBook Pro to do so as well... Which leaves you in the unfortunate situation of things mysteriously not working as advertised on the surface.

Digging into the monitor's Manual may contain some answers though.

The manual does include a somewhat cryptic note about using HDMI with a PC...

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And there is a series of notes that imply that 4k@60Hz may only be available if you enable "HDMI Ultra HD Deep Color" (in the Picture Adjust menu).

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  • Are you able to use / borrow a 4k DisplayPort monitor to verify the USB-C output from the laptops?
  • Are you able to use / borrow a system with 4k HDMI 2.0 output, to verify the Monitor's input?
  • Have you tried both HDMI inputs on the monitor?
  • Have you tried enabling "HDMI Ultra HD Deep Color"?
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  • Thank you for your very nice answer. My problem was indeed the "HDMI Ultra HD Deep Color" mode which I had not turned on. Unfortunately the other answer also gives this solution, and it was there before this one, so I feel that I should award it the reward. Thanks for helping nonetheless! – charel-f Jul 7 at 21:13
  • ha, so it does... no problem! – Attie Jul 7 at 21:31

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