Why 5120x1440 Doesn't Work with Apple M1

I have a Mini M1, 49" Samsung CRG9, no additional software.

I connect with a DP cable from Amazon that cost about £12.

On my monitor I set it to 60Hz and DiplayPort V1.2

No issues whatsoever. Wakes fine. Sleeps fine. No lockup’s. It’s just fine.

Agreed it 60Hz but not 120. I don’t play games so it’s totally irrelevant for me.

Exactly. So far the solution Davbit gave of using that 8k usb c to DP cable , plus SwitchResX, being on MacOS 11.1+, and having to get the CaliDigit TS3 Plus dock has been the only thing to make this a consistent and reliable setup.

I've got 5120x1440 @ 120HZ working out of the box with a Cable Matters USB-C to DP adapter + Cable Matters 8K DP cable that I've linked on the first page or two. This is with an AOC AGON 49" ultrawide.

I haven't seen anyone with a Samsung G9 succeed out of the box and everyone I know with an AOC AGON is working fine, so depending on if your LG is more like the Samsung or the AOC is going to determine your success.

Some very good news announced over the past few hours which should help all of us

https://9to5mac.com/2020/12/24/m1-mac-with-ultrawide/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+9To5Mac-MacAllDay+%289+to+5+Mac+-+Apple+Intelligence%29

Just wanted to pop in here and give some good news...

Just bought my first Mac Mini. Of course, it's an M1.

My biggest fear was that it would not drive my 46" Samsung CRG9 (I think that's the model).

Taking the advice of a YouTube video, I installed the next version of Big Sur. I'll let you figure that out. My post was removed by the agressive moderation here in trying to help people get their display problems fixed because I mentioned the "B" word.

In any case, I was immediately able to get 5120x1440 resolution in my choices of 60Hz, 100Hz and up.

My display is performing wonderfully. No issues whatsoever.

I am using a 40GB/60HZ TB3 cable from the Mini to a Caldigit dock. Then from the Caldigit dock I use an ordinary display port cable.

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.

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

I was able to use 5120x1440 @120Hz by installing and using the SwitchResX utility.

True. After I installed the 11.1 Beta I can use DP 1.4 without any issues when waking up and with 120Hz. Although I still need to use SwitchresX to get 5120x1440

Yes 11.1

Just noticed that my cable may not be a true 1.4.

New one being delivered today. I’ll let you know.

My display now works with 11.2 (so far) at 5120 x 1440 @120hz SDR on DP1.4 wFreeSync on.

New mid-Rez modes also seem to exist (HDPI?). More to test.

That CalDigit guy doesn't know his own product or Thunderbolt.

First of all, 5120x1440 60Hz is less pixels than 4K 60Hz so it requires less bandwidth than 4K 60Hz so DisplayPort 1.2 is sufficient. The Dock supports DisplayPort 1.2, so it is sufficient for 5120x1440 60Hz 10bpc.

HDR is a feature of DisplayPort 1.4 but the bandwidth required is the same (at least 10bpc). I think the CalDigit uses the Alpine Ridge Thunderbolt controller, so its output will be limited to DisplayPort 1.2 so maybe HDR and DSC won't be supported from that Thunderbolt dock. Newer Thunderbolt docks use the Titan Ridge Thunderbolt controller and can support DisplayPort 1.4 features (HBR3, HDR, DSC).

Standard USB-C cables should be fine, as long as they support 10 Gbps USB speeds since DisplayPort 1.2 only requires 5.4 Gbps per lane. Actually - if the display uses the USB-C connection for USB 3.0 ports, then this is not sufficient because the cable will only have two lanes for DisplayPort instead of the require four lanes. Some displays have an option to switch to USB 2.0 over USB-C so that the USB-C cable can have four lanes of DisplayPort. Two lanes of DisplayPort might be sufficient if DSC is supported (requires DisplayPort 1.4) but you probably don't want to rely on that.

For USB-C to DisplayPort cables, I don't think it matters unless you want to try to get 120Hz - then you should make sure they support DisplayPort 1.4 (8.1 Gbps per lane). The cable doesn't include USB so there will be 4 lanes of DisplayPort.

Have you tried my solution ? it works perfectly at home I also have a samsung 49" and I work with a resolution of 5120x1440p with 120Hz

Just install a small application available here: https://github.com/Eun/DisableMonitor

if connecting by display port change the settings on the monitor from 1.4 to 1.2.

UPDATE:

With SwitchresX things are working fine, with the Anker Dongle an the HDMI cable