Why 5120x1440 Doesn't Work with Apple M1

Amendment to my previous post. Everything works but if I set DP1.4 on the monitor it won’t wake from sleep so I’ve left it at DP1.2 and everything works fine.

Really not sure what the DP1.4 issue is. It is a 1.4 cable.

Make sure you set everything up on the monitor and then turn everything off and on.

What I’ve found is it doesn’t like plugging and re-plugging cables in and out while it’s on. If you do you’ll end up with lots of black screens and frustrations.

This cable gives me 120hz @5120x1440 with no issues. Have to use it on DP1.2. It does not work with DP1.4 setting.

Cable Matters 8K USB C to DisplayPort Cable (USB-C to DisplayPort 1.4 Cable/USB C to DP Cable) 8K@60Hz, 4K@60Hz, 2K@144Hz in Black 1.8m - Thunderbolt 3 Port Compatible for MacBook Pro, Dell XPS https://www.amazon.co.uk/dp/B01LYD2Y19/ref=cm_sw_r_cp_api_fabc_JX4NDVT3BGQXKNYQ0XK4?_encoding=UTF8&psc=1

Is the display connected directly to the DisplayPort 1.2 port of the TS3 Plus?

https://www.caldigit.com/ts3-plus/

Either you're not connected directly to the TS3 Plus, or you're not using 5120x1440 120Hz or the pixel format is not 4:4:4. I don't know how to get pixel format from macOS on M1 Macs, but the script at https://gist.github.com/joevt/e862b0088ef58b9144877d01401bcee8 should show what timing you are using.

You could be using 5120x1440 scaled down to 3840x1080@119.974Hz

Can someone explain the problems with the USB-C and Thunderbolt ports?

I had a situation yesterday with my M1 Mac Mini and my Internet connection. I have 1GB of Internet yet the speed was reduced to less than 100MB. I had to reboot the M1 to gain my connection speed back.

BTW, the Internet is coming through my Thunderbolt cable which is connected to a CalDigit dock which has an ethernet connection to it.

I haven’t seen any known issues with the USB-C/Thunderbolt ports. This thread was about the issues related to the software issues with Big Sur negotiating certain resolutions over certain ports, which seems to have been substantively resolved in 11.2.

Assuming you are saying the negotiated link speed of your CalDigit to your Internet router drops to 100mbps, the most common cause of this is your network cable. You could try swapping this. If you aren’t sure if it was your link speed or not, note the color of your network connection light for the network port your connected to and then note it again the next time it drops to 100. If the colour changes then you have a network port/cable link speed issue and can try another cable... or if the issue happens enough, just try a new cable and see if it resolves it.

Since you are using the Mac Mini, when that happens, try switching your connection from your internet modem to your Mac Mini instead of your CalDigit to see if the problem persists.

If this doesn’t help, suggest you start a new thread to see if others have a similar problem.

Thank you for your reply and assistance.

It's not the cable as I swapped out the Mini for my Intel 16" MBP and there were no Internet speed reductions.

Sadly, I just returned the Mini to Apple. The Internet speed issues were not the only problem. When the Mini rebooted there was a 100% CPU load that lasted over five minutes and slowed everything to a crawl.

It appears to me, that despite the improvements of the M1 chip, the Mini is still substandard when comparing it to the 16" MBP with 4x the memory. I think it's better to wait until the Mini is eventually refreshed and a more powerful chip with more ram options is available.

This is the same thing mine is doing now. I've tried the Cable Matters usb-c -> Displayport pigtail thing (which won't even wake the monitor up) and some other generic usb-c->dp cable, which claims 8k support (lmao) and I can get 5120x1440, although the font anti-aliasing goes away, and the scaling looks like garbage, plus what's happening in that screenshot, the input indicator popup just blinks on and off the whole time.

Does anyone know of a cable that works properly, or are the only people who are able to use their new M1 mini those who are willing to spend another 20% of the cost of the entire computer on a fancy dock?

Why couldn't they have just put a displayport plug on the back of the M1 mini is beyond me. I'm willing to try one more cable, but if they can't even get this thing to talk to an ultrawide monitor that's been out for years now, I'm just going to have to deal with Lightroom taking 6 seconds to open instead of 4 and keep using my windows machine.

Atrocious.

A USB-C to DisplayPort cable is just a cable - it does not fix problems with the source. It can do 8K only if the source supports 8K. Maybe the USB-C ports of an M1 Mac have voltage or signal problems or don't read the e-marker chip of some cables properly or something like that. Putting a Thunderbolt dock between the M1 Mac and a display can clean up the signal. An M1 Mac that can't get out a proper DisplayPort signal may be able to get out a Thunderbolt signal. A Thunderbolt dock takes Thunderbolt data from the M1 Mac and recreates a DisplayPort signal from that.

I'm having the same issue except I'm running BigSur 11.2.3. I have the recommended DP1.4 cable that was shown in that youtube video, and I even tried EasyRes to see if that would work. Somethings up with the updates and I really hope Apple takes care of this. I have a 5120x1440 @ 120hz Viotek 49" monitor and I'm out of ideas. If anyone has any other ideas or tips/tricks/fixes that they know of please let me know.

Folks, stop saying "it's working with this cable". It doesn't. You might be able to get a picture after some fooling around, but there is no HiDPI setting that's even remotely nice looking, and your fonts are always going to be either too small to read and blocky, or overblown and zoomed in to the point where the letters are quarter-inch tall.

I returned my mac mini, I'm over it.

Clearly there are still issues that Apple has yet to resolve, but that doesn't negate the fact that for some of us, 5120x1440@120hz is working perfectly fine through bootup, sleep, wake, and shutdown as expected. It all comes down to the combination of cable and monitor and settings on the monitor. Admittedly, I had issues early on, but once I got it working, it's been stable. The resolution is pixel perfect for 5120x1440, not zoomed in or out, jagged, fuzzy, or distorted. Using an AOC AGON 49 Super Ultrawide and the Cable Matters USB-C to DP adapter + DP cable. I'm running SwitchResX because it helped before MacOS was updated and I just never uninstalled it.

As shown in my previous screenshots , it is set to 5120x1440 @ 100Hz.

I previously were using they screen with Windows either, but there I had to scale it to 150% to be able to see anything. Weird twisted world. How do you switched this page here to dark mode ?

One difference I'm seeing is that you still have the HDR option showing in Display preferences.

Can't think of any specific reasons for why they're different though...