M1 MacBook Pro - External Monitor color issue

Hi All -

So… I made the leap and went all in with the M1 MPB with 16/1tb. I also picked up a 35 LG ultra wide (lg-35wn65c-b along with the Caldigit TS3}+

As I am setting things up on the M1 - manually installing the key apps - decided not to do migration assistant this time around (less old cruft) … I am connecting the 2015 15" MBP via HDMI. All good there. Looks decent. Whites are white, black is black.

The issue is that I’m just about ready to move over to the M1 - connected it via display port on the LG to the CalDigit. Then CalDigit to M1 via USB-C. Sends power and A/V.

My blacks are now grey and whites are muted. I’ve mucked around with sooo many options/settings… all for not.

Wondering if I went with a USB-C monitor (LG makes another version 1" smaller) to the CalDigit if that would help?

Anyone have thoughts? Ideas?



PS. I ordered all of this last month as it as a BDAY gift to myself! It was a biggie! :slight_smile:

You may want to confirm that you should not replace the USB-C cable with a true thunderbolt cable.

I have an MBP 16in attached to an LG 27. The only port that worked to give full access to all bells and whistles is going into the HDMI monitor port through a thunderbolt to HDMI adapter. I could not use the USB-C/thunderbolt cable that came with the monitor, nor could I go through a USB-C multi-port dongle (Anker 7-port). All such options gave limited options and in some cases bad behavior on the monitor.


Hmm… Interesting idea/thought…Though I am using the cables that came with the respective parts… i.e. Display Port came with the LG and the USB-C came with the CalDigit.

Tempted to upgrade the monitor to the next level up (LG 34WN80C-B) that has USB-C vs DP… and see if that solves the issue. I lose built in speakers and 1" of “ultra wideness”, neither of which are a deal breaker.

Lastly, I could just skip the ultra wide and go with a 32 4K and call it a day.

I cannot speak to whether the Display Port works on the monitor to give the full range of options. As I noted, my LG 4K 27in only seems to work in full mode through the HDMI. And the information on the monitor itself was essentially absent, so I had to do a lot of mucking about to discover this.

I would validate whether you need a true thunderbolt cable versus a USB-C. Here again, I thought that my Anker (thunderbolt) dongle to HDMI would work. But it did not. I ended up with these:


Have you looked at your color calibration settings in System Preferences?

The CalDigit T3+ comes with a Thunderbolt 3 cable — not USB-C…

I hope proper monitor calibration will be possible soon…

I was thinking similar issue and that might be a very inexpensive solution to try. Also for $15, easy to hold onto if/when we all start traveling again and I’d use for conference talks.

Yep. Tried all sorts of color calib stuff! No luck.

It seems like an obvious one, but just in case… have you tried turning it (the monitor) off and on again?

I have exactly the same MBP config and had it plugged into an LG monitor and I was also losing my mind over a washed out screen colour which no amount of monitor or computer settings fiddling would fix. Then I turned the monitor off and on again and it’s been fine ever since.

As a side note, from time to time the same monitor would start in “HDR mode” on my (Catlina) Mac mini 2018. Again, turn it off and on again solves it.

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I seem to remember a similar statement on the Amazon reviews for my LG. Turn OFF the HDR mode.


I have a Kensington Thunderbolt 3 (TB3) dock. I connected it to my M1 MacBook Air with a TB3 cable, then connected my 27" 4K LG monitor to it with a USB-C to DisplayPort cable and all the colors look fine. Note that I am not using an adapter. The cable is USB-C on one end and male DisplayPort on the other end which I plugged directly into the monitor.


To clarify my problem, it was nothing I turned on or off. It only appeared on startup of the Mac mini.

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Ya… I’ve turned it off/on a few times as well as restarted the M1.

I did order the HDMI dongle. Arrives tomorrow. Will report back if that fixes it. If not, I plan on taking the M1 with me to costco… plugging it into a 32" Samsung 4K monitor there have there on display. It’s the same price I believe albeit not Ultra Wide, bit I’d get 4K vs 2K …etc. pros/cons always exist.

I’m not so sure I can turn off HDR… there are settings avail via the on screen display… with HDR effect being one of them, and I’m currently using “cinema” with the old 2015 MBP… as it gets me the black background etc. That said… not seeing a way to turn an HDR setting off.

That was the fun part of my HDR problem. Whatever mode the monitor was in did not seem to be one I could set/unset myself!

However, the washed out issue with the M1 MBP was a once-only problem for me, cured by the same trick.

I’m curious what you found out, if anything?

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So that is HDR Mode on the LG, right? I have an LG 27UL850 and it has a setting under “General” that’s called “HDMI TRA HD Deep Color” and it is set to on, I assume that would be it? Problem is, it’s greyed out so I can’t change it. Tried various picture modes but it stays greyed out…

I would also be curious about that.

I think the HDR mode is only active with certain combinations of input cables. High quality HDMI or DisplayPort come to mind.


It is definitely on with my HDMI cable. It says “HDR” on the OSD every time the display turns on…

Let’s take a step back for a moment before we end up tracing back on who said what when.

The baseline that I can support by my tests is that the LG 27in 4k monitor will not provide full access to all possible controls unless you are using a proper (high-quality) HDMI input. All attempts to use USB-C fail. All attempts to use USB-C to HDMI dongles or hubs that do not support the full specs needed to drive the HDMI at is full specs also fail. Failure is indicated by having only limited access to the basic settings on the monitor. Failure is also indicated by having a washed out screen in some cases.

I have heard and strongly believe that the absolute best option to drive a 4k or above monitor is to use the best quality USB-C/thunderbolt to Displayport cable that can be found. All other options are roll the dice.

Finally, I can only say that somewhere on the Amazon reviews for the 4k LG monitor, I recall reading that one has to toggle or turn off or pay attention to the HDR setting mode. I suspect now without clear evidence that this caution is only required when your cables are not the best. Perhaps, sometimes, maybe some folks get the monitor to “recalibrate” itself to work properly by doing some toggle of some HDR setting even though the real culprit is the poor quality cables that they are using.

I have really been very pleased with my LG 4k in the meantime and have found no reason to purchase a USB-C to Displayport cable to solve any remaining (unknown) mysteries.