M1 MBP & LG 34 inch ultra wide 5K2K

[itsphilgeorge]

One possibility is that the GPU can do 2 of 10 at a rate of 3 each but not 1 of 20 at a rate of 6.
Where 1 and 2 are stream counts, 10 and 20 are pixel counts, and 3 and 6 are data rates (substitute those numbers with numbers that make sense). The GPU in this case is limited by the max data rate for a single stream. It's the same problem as why we have CPUs with 20 cores at 3 GHz instead of CPUs with 10 cores at 6 GHz.

In an Intel GPU, they have to use multiple CRTC's (pipes?) to handle a large resolution.

Remember in the olden days when 4K displays first came out, GPUs were doing two 1920x2160 tiles instead of one x 3840x2160 tile (using MST over a single DisplayPort connection).
The tiled display examples I gave (intel with Dell 8K, or old 4K displays) have the limitation in the display but you can image a similar limitation occurring in the GPU. It would be useful to find a document or video example where the limitation is in the GPU alone. Actually the video talks about single tile displays that require multiple pipes and they mention the DSC case (which uses multiple stripes?) and they mention clock limits, etc.

I don't believe the limit is 6K max frame buffer; I'm just saying that there could be reasons for a limit.

Yep. Agree with all of that. I guess we won't know unless Apple ever acknowledges it and it looks like they won't.

Let's hope that the M2 resolves it and then I'll just sell the M1 and be done with it.

 

[itsphilgeorge]

I have this monitor for work and experienced similar problems with my ThinkPad. It only worked (in Linux and Windows) using DP 1.2

I then installed the LG software and installed a firmware update recently for the monitor and now it just works via TB3 connected to the ThinkPad. Full resolution using DisplayPort 1.4. Do the problems with M1 Macs are the same with the newest firmware?


I plan to get an M1x/M2 MacBook Pro when they release and hope that the screen will work without problems then :/ Anything else would be disappointing

Yep. No change with the latest firmware upgraded using a Windows machine.

Also tested on MacOS 12 Beta 12.0 (21A5248p).

 

[grmlin]

Yep. No change with the latest firmware upgraded using a Windows machine.

Also tested on MacOS 12 Beta 12.0 (21A5248p).

Well, good I didn't go for a M1 then yet... :/

 

[jcolby]

This is driving in total 24,484,608 pixels furthermore, it does so comfortably. This is approximately the same amount of pixels as the 24,883,200 it must drive when running our desired resolution on a single external display without the internal display running.

That is 2 streams, though, which may be easier somehow.

We cannot know for certain, but the behavior is generally similar to 2020 Intel iGPU macs, which can reportedly hit one more higher fractional retina level of "looks like" 3360, but not 3840, so I suspect the underlying cause of GPU limitation is also similar (rather than a new imposed M1-only artificial block by Apple).

 

[Lemon Olive]

Just checking in. Does the M1 work with external displays yet?

 

[j222]

...Anyway, please let me know if you have any lingering questions. I understand this will be a discouraging perspective to many on here, so I am happy to clarify the best I can...

Thanks jcolby for your time on this. So, if this is correct (I have no idea) -- then the HiDpi scaled resolutions we are hoping for will never be possible with M1. If that's the case - why wouldn't Apple just say that? Many people have been inquiring and spending time on this.

You mention that Apple doesn't specify that these HiDpi resolutions will be available, which is true - but for Mac mini m1, it says:
"One display with up to 6K resolution at 60Hz connected via Thunderbolt and one display with up to 4K resolution at 60Hz connected via HDMI 2.0". This leads me to believe any display up to 6K is totally fine with M1 -- and obviously very few people want to use most 4k, 5k, or 5k2k displays at native resolution. In my opinion this is extremely misleading from Apple. I (and likely many others) would have never bought an M1 knowing if this was the case. If they were more specific, saying we recommend display X,Y or Z, then that would be fine. When I called Apple they recommended LG 4k-24 and LG 5k-27, and they said if other monitors don't work optimally, then its the display manufacturers fault.

If M1 text rendered half decently on even a 1440p display - I would be happy, but Apple has disabled font smoothing / and any other font rendering options in Big Sur / M1, so you are now forced to go with a 4k or higher display for crisp text, but then you cannot scale the resolution to something practical.

If people know for sure one way or the other - they can then decide between using one of the very few monitors that is properly supported, or selling the M1. I'm still confused...

(Sorry to ramble - I'm not asking you or anyone to explain why Apple does what it does - just commenting in context of your information...)

 

[anchoricex]

The cynic in me feels like Apple is just trying to say "well if you want to use an external display, you have to use one of OUR external displays we sell on our store"

And that thought just seems so dreary and sad that I want to cry.

For sale, LG 5k2k. 😭

 

[Doubleslash]

The cynic in me feels like Apple is just trying to say "well if you want to use an external display, you have to use one of OUR external displays we sell on our store"

And that thought just seems so dreary and sad that I want to cry.

For sale, LG 5k2k. 😭

The problem also exists with their XDR display. IIUC it won't support the same scaled resolutions on an M1 chip as on an Intel gear. As a result you paid 6k for display and you have less screen real estate with an M1 machine than with an Intel machine.

 

[grmlin]

The problem also exists with their XDR display. IIUC it won't support the same scaled resolutions on an M1 chip as on an Intel gear. As a result you paid 6k for display and you have less screen real estate with an M1 machine than with an Intel machine.

Just so I get this right. The 5k2k works at 100% in its full resolution but scaling doesn’t work?
I’m planning to get the next iteration of arm MacBook for work and that would be a showstopper. I hope they’ll fix it with the next chips

 

[Doubleslash]

This is what this whole thread is about. Fractional scaling doesn't work. With the current M1 chips you can run an 5k2k display either at full, native resolution where everything is unreadably tiny or you can run limited scaled resolutions where everything is way too big.
The best resolution of 3840x1620 (rendered at 7680x3240) is missing on M1 devices, likely due to hardware limitations. It's the reason why I returned my M1 Mac Mini and hope that M1x devices have this working correctly.

 

[grmlin]

This is what this whole thread is about. Fractional scaling doesn't work. With the current M1 chips you can run an 5k2k display either at full, native resolution where everything is unreadably tiny or you can run limited scaled resolutions where everything is way too big.
The best resolution of 3840x1620 (rendered at 7680x3240) is missing on M1 devices, likely due to hardware limitations. It's the reason why I returned my M1 Mac Mini and hope that M1x devices have this working correctly.

Thanks. I’ll wait and see what the next chip can do.

 

[the future]

It is too opinionated, though, to call 3840 the „best resolution“. I have an Intel mini and still prefer to use 3008.

 

[tommiy]

Its is sad to see the lack of resolution capability on the M1. I too returned my M1 because I could not get it to provide a usable resolution on my displays where text was the right size and not blurry. I returned to my 2017MBP which handles it perfectly for my needs. The lack of laptop standard features such as this is problematic. But as many have pointed out it is an entry level device. Maybe in the future either the hardware or the software may support fractional scaling. The lack of response from Apple also means when the next version comes out i definitely will not be rushing to that....

 

[shapesinaframe]

Is there a list of ultra wide monitors that do work (with hidpi scaled resolution) with the m1?

 

[shapesinaframe]

Or if not a list, then a way to know what scaled resolutions are possible with a given native resolution?

 

[mario0]

Same issues here... I have a Macbook Pro M1 and LG 34WK95U display. I found this thread on Google.

It's very disappointing that hidpi doesn’t work and you have to work with native 5120x2160 or scaled 3008 x 1269 which is also inacceptable.

So at the end I will switch “back” to a Macbook Pro Intel which is working fine with my LG monitor.

Hopefully the new M1X or M2 in future is no beta product anymore.

 

[henrys]

I've just got the M1 MacBook and the screen looks like crap on LG 5K HDR monitor

I changed DisplayPort settings to 1.2 from 1.4 in settings of the monitor and I am now getting 5120 x 2160

Previously it was limited to 3XXX x XXXX

 

[mario0]

I've just got the M1 MacBook and the screen looks like crap on LG 5K HDR monitor

I changed DisplayPort settings to 1.2 from 1.4 in settings of the monitor and I am now getting 5120 x 2160

Previously it was limited to 3XXX x XXXX

Make sure that you have installed MacOS 11.4 and latest firmware for the LG monitor.
DP1.4 works fine with 5120x2160 but it is not usable because everything is to small.

 

[henrys]

Make sure that you have installed MacOS 11.4 and latest firmware for the LG monitor.
DP1.4 works fine with 5120x2160 but it is not usable because everything is to small.

I'm running off 11.0, should I update? I don't to mess it up. I have never updated the LG monitor.

Everything is too small but what can you do

 

[mario0]

I'm running off 11.0, should I update? I don't to mess it up. I have never updated the LG monitor.

Everything is too small but what can you do

Why you don't make updates? AFAIK 11.2 or 11.3 has fixed the DP1.4 bug.
Also make sure the monitor has latest firmware. You can do that with LG OnScreen Control.

 

[grmlin]

Why you don't make updates? AFAIK 11.2 or 11.3 has fixed the DP1.4 bug.
Also make sure the monitor has latest firmware. You can do that with LG OnScreen Control.

It does not fix the scaling issue though, correct?

 

[5425642]

Why you don't make updates? AFAIK 11.2 or 11.3 has fixed the DP1.4 bug.
Also make sure the monitor has latest firmware. You can do that with LG OnScreen Control.

LG OnScreen Control don't seem to work for me on my m1 Aldo I do have the 32UN880

 

[Wolf1701]

This thread is spiraling down.

LG 34WK95U (-W) with M1:

1) CAN display 5120x2160 (everything small)
2) CAN display 3008x1269 hidpi
3) CAN'T display 3840x1620 hidpi (most wanted resolution)

LG OnScreen works with M1 (monitor firmware upgrade), TB3 cable

 

[AlphaCentauri]

This thread is spiraling down.

LG 34WK95U (-W) with M1:

1) CAN display 5120x2160 (everything small)
2) CAN display 3008x1269 hidpi
3) CAN'T display 3840x1620 hidpi (most wanted resolution)

LG OnScreen works with M1 (monitor firmware upgrade), TB3 cable

Or rather going in circles

I would add:

4) CAN display 2560x1080 hidpi (everything too big for many, but perfect for me)

 

[shapesinaframe]

Or rather going in circles

I would add:

4) CAN display 2560x1080 hidpi (everything too big for many, but perfect for me)

Thanks for posting this.

2560x1080 is the resolution I was using on my 3440x1440 display with Intel MBP and it’s good to know I can get it with this 5K2K display and M1.