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Help: M4 Mini limited to 4k @ 60hz over 8k HDMI 2.1 cable

EvilEvil

EvilEvil

macrumors 65816
Original poster
Jan 8, 2007
1,242
2,066
New York City
I just got my M4 Mini and plugged it into My LG C2 4k OLED TV and can only get 4k @ 60hz max. I thought it was supposed to support 4k @ 120hz over HDMI?
 
General > External Devices > HDMI Settings > HDMI Deep Color > 4K

Did you not have that activated this whole time?

Also make sure you change your HDMI input to "PC" in the TV Settings.
 
Cosmo M3 said:
General > External Devices > HDMI Settings > HDMI Deep Color > 4K

Did you not have that activated this whole time?

Also make sure you change your HDMI input to "PC" in the TV Settings.
Click to expand...
I just checked. It's greyed out and won't let me change it. Is my HDMI cable the culprit?
 
The M4 Mini definitely supports 4K 120Hz. Works fine on my LG C4 - no tweaking necessary, just plugged it in. I suspect your cable.
 
EvilEvil said:
It indeed was the cable. I just tried another cable and it worked!
Click to expand...
Hey, I'm still waiting for my M4 Pro mini to deliver, and I intend to use it with my LG C3 and an ASUS ROG OLED monitor side by side. could you confirm with your C2, you're able to have 4K 120Hz HDR from the mini? and what's your resolution scaling?

the experience I've had with this TV and my M2 Max laptop, is that if I want HDR, the maximum resolution scaling and refresh rate is 1440p and 100Hz, anything higher would make me lose the HDR option, and the non HDR on LG C3 looks awful for macOS.
 
@foojesus I can confirm my base M4 mini gets 4k 120hz with HDR if you use the proper cable on my LG C2 42". The MacOS resolution scaling is kinda wonky, so I don't use HiDPI and just leave it at default 4K resolution.
 
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EvilEvil said:
I just checked. It's greyed out and won't let me change it. Is my HDMI cable the culprit?
Click to expand...
Could be. HDMI sucks. I've had all manner of problems with HDMI cables.

I can confirm that i am able to run 4k @ 120 (or higher i forget, maybe 144 - my montor is 160hz, just remember 160 doesn't work) on an M1 pro via USB-C. I would expect the M4 to do as well or better than that.
 
Cosmo M3 said:
@foojesus I can confirm my base M4 mini gets 4k 120hz with HDR if you use the proper cable on my LG C2 42". The MacOS resolution scaling is kinda wonky, so I don't use HiDPI and just leave it at default 4K resolution.
Click to expand...
yea the UI in native 4K is just too small to read. I did some digging, with resolution scaling like 1440P, macOS is actually rendering 5K (2880p) and then sizing it down to 1440P to the monitor, however 5K120HzHDR requires more bandwidth than what HDMI 2.1 can achieve.

monitors that support high refresh rate achieves this by have DSC implemented that compresses the stream while having no visibly artifacts. However, LG C series TV does not implement DSC, hence it cannot achieve 4K120Hz at HiDPI with HDR on macOS.
 
dgdosen said:
42"? What resolution do you run? Just curious as the C4 prices drops start.
Click to expand...
It will run 3840x2160, but I usually use the “default” 1920x1080 for productivity work because of the font size. The downscaling works fine - better than in Windows.

EDIT: Yes, C4 42.
 
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