DIY 5k Monitor - success :-)

[yurikhan]

at 5K, I find the text too small to be readable

That’s actually a consequence of Apple’s definition of retina. They preach ~220ppi and use 2× scaling. However, the CSS specification assumes 96 ppi at 1× at a distance of one standard arm’s length, so the ideal pixel density for 2× is 192ppi, which roughly corresponds to 4K @ 24″ or 5K @ 32″.

With 5K @ 27″, everything is 15% smaller than ideal; or you have to bring the monitor 15% closer (which has been said to be harmful to the eyes).

 

[wearyoftrying]

Is anyone using USB-C input of the R1811 with a Macbook? Based on at least one poster (early in this thread) saying using it fried the USB port on his Macbook, I assumed this should be avoided.

 

[i486dx2-66]

That’s actually a consequence of Apple’s definition of retina. They preach ~220ppi and use 2× scaling. However, the CSS specification assumes 96 ppi at 1× at a distance of one standard arm’s length, so the ideal pixel density for 2× is 192ppi, which roughly corresponds to 4K @ 24″ or 5K @ 32″.

With 5K @ 27″, everything is 15% smaller than ideal; or you have to bring the monitor 15% closer (which has been said to be harmful to the eyes).

You might know more- but it sounds like the CSS standards group *tried* to go the right path, and ended up bailing because too much of the internet revolved around assumptions based on PCs, and standardizing on a flawed assumption was easier than breaking the internet...

CSS Values and Units Module Level 3

Note: This definition of the pixel unit and the physical units differs from the earlier editions of CSS1 and CSS2. In particular, in previous versions of CSS the pixel unit and the physical units were not related by a fixed ratio: the physical units were always tied to their physical measurements while the pixel unit would vary to most closely match the reference pixel. (This unfortunate change was made because too much existing content relies on the assumption of 96dpi, and breaking that assumption broke the content.)

Also, I don't know if we can really blame Apple's definition of retina here. The 5K 27" combo was an extremely logical step, as the 5120x2880 resolution is exactly 2x in each direction of the 2560x1440 that iMacs have used since 2009, which simplifies... everything. This display pixel density is a path others were going down as well (Dell's 27" 5K display came out before Apple's 5K iMac).

 

[JavD]

Apple M1:
Chipset Model: Apple M1
Type: GPU
Bus: Built-In
Total Number of Cores: 8
Vendor: Apple (0x106b)
Metal Support: Metal 3
Displays:
DP:
Resolution: 5120 x 2880 (5K/UHD+ - Ultra High Definition Plus)
UI Looks like: 2560 x 1440 @ 60.00Hz
Main Display: Yes
Mirror: Off
Online: Yes
Rotation: Supported

Nope, only when the MacBook Air's internal display is detected. The connected monitor does not natively have a brightness control within system settings.

thanks for your info.

1. under DP , do you get the item: "Automatically Adjust Brightness:": Yes or No?
2. Could you set the display to full resolution of 5K, not "UI Looks like: 2560 x 1440 @ 60.00Hz" ? but 5120x2880 @60Hz, yes, just for a test.
3. within macOS: About This Mac => Displays: Do you get the display's name as imac 5K 27" something lie this represents the panel's real identification, etc.?

/BR

 

[i486dx2-66]

thanks for your info.

1. under DP , do you get the item: "Automatically Adjust Brightness:": Yes or No?
2. Could you set the display to full resolution of 5K, not "UI Looks like: 2560 x 1440 @ 60.00Hz" ? but 5120x2880 @60Hz, yes, just for a test.
3. within macOS: About This Mac => Displays: Do you get the display's name as imac 5K 27" something lie this represents the panel's real identification, etc.?

/BR

1) I can't recall... I would have to check next time I hook that computer up. But by default (without MonitorControl or BetterDisplay installed), macOS does NOT have the ability to adjust the display brightness via software.

2) Yes, that worked fine, and the monitor reported 5120x2880 as well. I also tried changing the scaling modes presented in the monitor's OSD (between "full" or "fill" - can't remember the name, but the one that stretches to fill the screen, and the 1:1 setting), and even with pixel-level test patterns couldn't tell any difference.

3) This monitor presents itself to the Mac as simply "DP" when connected to the display port, or "HDMI" when connected via HDMI. I don't know if the T18 itself provides these designations, or if macOS automatically applies them because the monitor doesn't provide info? The monitor does not otherwise give any name/brand/model info that I can see. It also doesn't correctly self-identify the size - I think it identifies as something small, I want to say 13.9", when in 5120x2880... but 24" when running at 3840x2160.

 

[yurikhan]

You might know more- but it sounds like the CSS standards group *tried* to go the right path, and ended up bailing because too much of the internet revolved around assumptions based on PCs, and standardizing on a flawed assumption was easier than breaking the internet...

Yeah. Latest CSS 1 and older versions of CSS 2 suggest a reference pixel size as 1/90 in. Newer CSS 2.1 and CSS 3 define 1px as exactly 1/96 in.

The 5K 27" combo was an extremely logical step, as the 5120x2880 resolution is exactly 2x in each direction of the 2560x1440 that iMacs have used since 2009, which simplifies... everything. This display pixel density is a path others were going down as well (Dell's 27" 5K display came out before Apple's 5K iMac).

The 90dpi suggestion has been in CSS 1 ever since 1996. Panels should have been designed for integer multiples of roughly that, slightly less dense than they are. Maybe 2304×1296 27″. That would have simplified everything.

Now, everything would be good with non-integer scaling if it were not for pixel-based non-photographic images (icons, line art, pixel art). These can only be meaningfully upscaled with a nearest neighbor algorithm at integer factor.

Sorry, pet peeve. Rant over.

 

[i486dx2-66]

Sorry, pet peeve. Rant over.

All good. 😁

The 90dpi suggestion has been in CSS 1 ever since 1996. Panels should have been designed for integer multiples of roughly that, slightly less dense than they are. Maybe 2304×1296 27″. That would have simplified everything.

In all fairness, the world was also a different place in '96. Facebook was still almost a decade away, just a fraction of the population had Internet access, and most computer users would have had the diverse range of local applications as their primary focus when using a computer. I wouldn't fault hardware manufacturers at all for ignoring the advice of a consortium founded just a few years prior.

 

[JavD]

1) I can't recall... I would have to check next time I hook that computer up. But by default (without MonitorControl or BetterDisplay installed), macOS does NOT have the ability to adjust the display brightness via software.

2) Yes, that worked fine, and the monitor reported 5120x2880 as well. I also tried changing the scaling modes presented in the monitor's OSD (between "full" or "fill" - can't remember the name, but the one that stretches to fill the screen, and the 1:1 setting), and even with pixel-level test patterns couldn't tell any difference.

3) This monitor presents itself to the Mac as simply "DP" when connected to the display port, or "HDMI" when connected via HDMI. I don't know if the T18 itself provides these designations, or if macOS automatically applies them because the monitor doesn't provide info? The monitor does not otherwise give any name/brand/model info that I can see. It also doesn't correctly self-identify the size - I think it identifies as something small, I want to say 13.9", when in 5120x2880... but 24" when running at 3840x2160.

Thanks for your reply.

I still doubt whether the T18 panel can be set to 5K(5120x2880) via single USB-C cable (w/o thunderbolt3), esp. when checking about the bandwidth needed for 5K vs. USB-C(USB3), as indicated here,

1. 5K resolution needs bandwidth: ~22Gbps (5120 X 2880 ~= 14.7MP);
2. USB-C: even the USB3.1 gen2. only comes with 10Gbps

I assume you have set the resolution to 2K(2560x1440) due to readability. That's why I am asking if you could check in System Preferenece => Displays => advanced settings with resolution list, if 5K(5120x2880) was listed there. OR
if you could have Windows e.g. installed via BootCamp, to check the resolution listing.

Another way to validate is:
while you boot up mac or light up the screen, at the right corner of the panel if information shows as

like this? (Not 4K(3840...), but 5K, i.e. 5120x2660@60.0Hz) ?

 

[joevt]

1. USB-C: even the USB3.1 gen2. only comes with 10Gbps

USB 3.1 gen 2 only uses two of the four super-speed wires in a USB-C cable, one for receive and one for transmit. The other two can be used for 2 lanes of HBR3 DisplayPort Alt Mode (8.1 Gbps per lane).

DisplayPort Alt Mode with USB 2.0 uses all four super-speed wires in a USB-C cable for 4 lanes of HBR3. That's 25.92 Gbps of DisplayPort data.

 

[JavD]

USB 3.1 gen 2 only uses two of the four super-speed wires in a USB-C cable, one for receive and one for transmit. The other two can be used for 2 lanes of HBR3 DisplayPort Alt Mode (8.1 Gbps per lane).

DisplayPort Alt Mode with USB 2.0 uses all four super-speed wires in a USB-C cable for 4 lanes of HBR3. That's 25.92 Gbps of DisplayPort data.

Strange that I am using T18 driver board got only max resolution of 3360x1890 via USB-C/DP mode with mbp M1.

 

[i486dx2-66]

Thanks for your reply.

I still doubt whether the T18 panel can be set to 5K(5120x2880) via single USB-C cable (w/o thunderbolt3), esp. when checking about the bandwidth needed for 5K vs. USB-C(USB3), as indicated here,

1. 5K resolution needs bandwidth: ~22Gbps (5120 X 2880 ~= 14.7MP);
2. USB-C: even the USB3.1 gen2. only comes with 10Gbps

I assume you have set the resolution to 2K(2560x1440) due to readability. That's why I am asking if you could check in System Preferenece => Displays => advanced settings with resolution list, if 5K(5120x2880) was listed there. OR
if you could have Windows e.g. installed via BootCamp, to check the resolution listing.

Another way to validate is:
while you boot up mac or light up the screen, at the right corner of the panel if information shows as

like this? (Not 4K(3840...), but 5K, i.e. 5120x2660@60.0Hz) ?

View attachment 2219279

I'm using a USB-C to DisplayPort cable... and I get that info bubble with the following text:

DP 5120x2880@60.0Hz H:175.5KHzPCLK:925.7MHz HDCP2.2Sink

 

[i486dx2-66]

Strange that I am using T18 driver board got only max resolution of 3360x1890 via USB-C/DP mode with mbp M1.

My 5K equivalents of your screen captures are attached.

 

[JavD]

I'm using a USB-C to DisplayPort cable... and I get that info bubble with the following text:

DP 5120x2880@60.0Hz H:175.5KHzPCLK:925.7MHz HDCP2.2Sink

thanks!
USB-C to DP1.4 for 5K is logical as discussed with @joevt about the bandwidth issue, so not USB-C to USB-C, which means the 65W power delivery via one cable solution is not possible as T18 described online?

That's what I am afraid of.
On the other side, if not USB-C to USB-C, then also missing USB functionalities incorporated, i.e. sound & USB hub on the driver-board.

I still hope the T18 producer could enable USB-C to USB-C with DP1.4 protocol or maybe Thunderbolt(TB) 3 protocol, so it can support 5K with power delivery as described. Hopufully it is just a firmware/software update, not because of missing chipset or forced to pay Apple the TB3 licensing fee.

On the other side, my personal feeling is the display quality from org. iMac 5K still superior to this with T18 driverboard(e.g. retina 2K scaled), do you agreed?
---
Back to the DIY topic, the original iMac comes with TB2 port, which support up to only 4K ext. monitor? would be nice to be able to connect to back to the iMac desktop with 5K incl. its dedicated AMD eGPU. Don't know if any solution on market. ;-)

 

[i486dx2-66]

On the other side, my personal feeling is the display quality from org. iMac 5K still superior to this with T18 driverboard(e.g. retina 2K scaled), do you agreed?

My panel is a 2014, with tons of dust between the layers... but otherwise it looks great.

Is your perspective perhaps skewed, in that the iMac 5K is (was) driving the panel at the full 5K, whereas your T18 setup via USB-C is driving the panel at 3840x2160?

 

[i486dx2-66]

Ok, after living with this for a few weeks, I have a few more questions for those who have converted iMacs:

1) My iMac has substantially less stuff inside, and the tilt balancing springs are now too strong. If something shakes the floor, the monitor tilts itself upward. 😁 Anyone else have this issue? And did you mod the springs, or just add some weight inside?

2) Due to my desk setup, the display sits a little higher than I'd like. Are the 21.5" and 27" stands interchangeable? (I presume the 21.5" stands are shorter?)

 

[yurikhan]

Got a Baseus cable that is advertised as HDMI 2.1, 8K@60Hz and 48Gbps, now looking at the EDIDs.

Both HDMI inputs seem to identify as manufacturer SGT, model 0, product name HDMI, serial number demoset-1, made in week 10 of 2019, max image size 53×30cm — corresponding to about 24″ diagonal. Advertises modes up to 4096×2160@60, 3840×2160@60.

Trying to add a 5K modeline, even with all modeline validation checks disabled, gives me an Unable to determine HDMI 2.1 Fixed Rate Link configuration error. I guess I won’t be using this monitor over HDMI any time soon, and I’m further convinced that DisplayPort is the One True video connector.

 

[i486dx2-66]

I guess I won’t be using this monitor over HDMI any time soon, and I’m further convinced that DisplayPort is the One True video connector.

I wish I could do some tests to confirm this, but I unfortunately don't have any devices capable of generating 5K over an HDMI interface...

But you said that you also couldn't get 5K over straight USB-C? I haven't tried it yet, but I would have thought the USB-C cable would be going via a DisplayPort interface internally? 🤔

 

[yurikhan]

But you said that you also couldn't get 5K over straight USB-C? I haven't tried it yet, but I would have thought the USB-C cable would be going via a DisplayPort interface internally? 🤔

Thing is, I have never had a demonstration that the Thunderbolt port in my laptop worked as such. Any cables advertised as Thunderbolt-to-Displayport, hubs advertised as Thunderbolt-to-HDMI-LAN-and-several-USB, and now just a straight high-bandwidth USB-C cable, fail to deliver video. (And I failed to raise this issue while it was under warranty, as it wasn’t a blocker.)

 

[JavD]

My panel is a 2014, with tons of dust between the layers... but otherwise it looks great.

Is your perspective perhaps skewed, in that the iMac 5K is (was) driving the panel at the full 5K, whereas your T18 setup via USB-C is driving the panel at 3840x2160?

Not really understood what you mean, but T18 described as capable of 5K with USB-C cable(+65W power delivery). Also I would eventually set to 2K(2560*1440), but I expect it'd keep its promise. esp. I was thinking of to retire my LG 4K monitor(w. 65W) single cable solution. Now I am not quite sure if I should get rid of the iMac 5K instead.

w.r.t. your tilting problem, yes you can adjust the spring inside, same design has also DELL stand.

Summary: from what I tested and read here, the only way for T18 to reach 5K is USB-C-to-DisplayPort, or DP-to-DP, not USB-C to USB-C or HDMI. The reason is most probably USB-C with T18 not Thunderbolt 3 certified.

 

[i486dx2-66]

Not really understood what you mean

It was in regards to this:

On the other side, my personal feeling is the display quality from org. iMac 5K still superior to this with T18 driverboard(e.g. retina 2K scaled), do you agreed?

Basically, my thought was that if you had only been able to drive the display at 3840x2160, then any image you looked at would have been scaled (by 1.3333x) to fit the panel, with an image quality hit as a result. So it would make perfect sense that the perception of the image quality would be worse than that of before the conversion, even if your chosen "looks like" resolution (1920x1080) was the same in both cases.

 

[mrdude42]

Updated my build:

 

[michaelsft]

Hi everyone, this thread has inspired me to give it a go and I recently purchased a cheap 2015 27” iMac with the LM270QQ1 panel which is, thankfully, in good condition. I have basically gutted it and put whatever I can on eBay (nothing selling but there it shall stay until it does!). My plan is simply to keep the shell and screen, I’m not interested in keeping a webcam or speakers.

Anyway, as I understand it I just need the right board and cables and I’m ready to go. I was wondering if there was a consensus on what would be appropriate for me hooking this up to a Mac Mini M2 Pro.

Ideally it would be a board without a fan with HDMI that outputs 5k@60Hz - does that board exist? Any tips for which board best suits my needs?

I read through things but there’s a lot of info in this thread so any advice would be gratefully received.

Thanks for reading
Michael

 

[davidg5678]

Hi everyone, this thread has inspired me to give it a go and I recently purchased a purchased cheap 2015 27” iMac with the LM270QQ1 panel with is, thankfully, in good condition. I have basically gutted it and put whatever I can on eBay (nothing selling but there it shall stay until it does!). My plan is simply to keep the shell and screen, I’m not interested in keeping a webcam or speakers.

Anyway, as I understand it I just the right board and cables and I’m ready to go. I was wondering if there was a consensus on what would be appropriate for me hooking this up to a Mac Mini M2 Pro.

Ideally it would be a board without a fan with HDMI that outputs 5k@60Hz - does that board exist? Any tips for which board best suits my needs?

I read through things but there’s a lot of info in this thread so any advice would be gratefully received.

Thanks for reading
Michael

The Haijing T18 should meet these criteria. It supports 5k@60Hz, is fanless, and would connect to your M2 Mac Mini. I think the right cable to connect it to your Mac Mini would be a DisplayPort to USB-C cable. It does have HDMI and USB-C as well.

I just got mine in the mail and am still testing it out, but I think I prefer it to my R1811 board (also it's cheaper).

 

[michaelsft]

The Haijing T18 should meet these criteria. It supports 5k@60Hz, is fanless, and would connect to your M2 Mac Mini. I think the right cable to connect it to your Mac Mini would be a DisplayPort to USB-C cable. It does have HDMI and USB-C as well.

I just got mine in the mail and am still testing it out, but I think I prefer it to my R1811 board (also it's cheaper).

Thank you very much for replying, much appreciated!

I am going on holiday for a couple of weeks so I think I'll reassess when I return but if you have any updates from your testing I'd love to hear how you get on. After reading I did have a feeling this might be the board for me. I was hoping by now there would be a drop in board that just worked without messing around and it seems like the T18 might be the closest we get.

 

[JavD]

It was in regards to this:
Basically, my thought was that if you had only been able to drive the display at 3840x2160...

I would (have to) go the USB-C to DP solution. Thus I'm also disappoint by T18 driver-board as it described as suport 5K via USB-C to USB-C with power delivery 65W.

Ideally it would be a board without a fan with HDMI that outputs 5k@60Hz - does that board exist? Any tips for which board best suits my needs?

Ideally would be one cable solution with USB-C (with TB3/4 support i.e. for DP1.4 and USB3 hub, etc.) and power delivery as well. Yet I understood mbp M1/M2 now has the MagSafe power connector. PS: as I have tested T18 via. HDMI, it can only support up to 4K(4096*), and with mbp M1 even lower resolution than(3840*2160), maybe you would confirm it eventually.

---
My further thought is about the complete setup of laptop <=> 5K if technically make sense. In fact, computer with external display is a desktop setup, eps. iMac has a dedicated GPU/graphic card, which would drive 5K display smoothly. If you use MBP with integrated GPU to drive a 5K display, that would consume a lot system resource, most probably comes with laptop temperature high and fan noise. Because laptop(mbp) is design focusing on mobile and desktop(iMac) is design for stationary performance. My 5 cents here.

So if we stick to the topic of 5K iMac DIY, my crazy idea would be how to make iMac eGPU external usable for my laptop to connect to, and via it go to screen. Is there any interface design for this?