I have looked all over the internet and I have seen this issue popup all the time, but none of the 'fixes' seem to work for me.

I have recently switched from a pc to a mac. I run 3x monitors off my computer and on PC I have had no issues what so ever.

I have a 2019 MacBookPro which is now running Big Sur. (I have recently formatted the computer also to start fresh after my switch from the PC about a month ago).

My initial 1080p monitors (hdmi to displayport) work perfectly fine on the pc, but on the mac I am having issues.

I use a Kensington SD4900P hub to connect all my bits and pieces to the mac. Everything works fine other than the displays.

I thought they might be the monitors so I upgraded all three to the LG UltraGear 27GL850-B 27" thinking that Mac work with LG to create a 5k monitor that LG would be the way to go, but still nothing is working for me.

I have purchased a USB-C to DisplayPort cable to see if this helps, but nope, nothing there either. The only difference with the cable running directly into the mac is I get a 'High Dynamic Range' option, which when ticked seems to work a bit, however, it does make my monitor really dull, which is a bit frustrating.

I have also tried resetting my SMC and also the following commands (all with a restart between them)

defaults write -g CGFontRenderingFontSmoothingDisabled -bool FALSE
defaults write com.apple.Safari CGFontRenderingFontSmoothingDisabled -bool FALSE
defaults -currentHost write -globalDomain AppleFontSmoothing -int 3
defaults -currentHost write -g AppleFontSmoothing -int 0
defaults -currentHost write -g AppleFontSmoothing -int 2
defaults write -g CGFontRenderingFontSmoothingDisabled -bool NO

Nothing seems to be helping. I have already spent upwards of $3k (nzd) on trying to get this to work I really don't want to have to go and switch back to my pc for work.

Are there any other suggestions that I can try to get this to work? It is also starting to give me a bit of a headache / sore eyes, which is not good as I stare at my screens all day.

I should also mention that my mac display is perfect.

2 Answers 2


So for my issue so far I have changed the view mode on the monitors from 'Vivid' to 'sRGB' and it seems to have sorted out the monitors a fair bit.

I will still try another cable, but for now, things are looking a lot better


Check the maximum resolution that is supported by the monitor cable. I had a similar problem as I was using an HDMI to miniDP cable which maxed out at 1080p.

Changing to a Display Port cable immediately resolved this issue.

In my understanding, you need a Display Port cable (version 1.2 or above) that supports higher resolutions (2k or 4k). Check out the image below for supported resolutions for different display port standards. Source link.

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