DIY 5k Monitor - success :-)

[PaulD-UK]

@kevinherring There is a possible alternative to the 4K R9513 that has USB-C input and 65W PD output - the R9516.
However StneTaskin only list compatibility with the 2015 21 iMac LM215UH1-SD(A1) screen, not the DS(B1) used in the 2017+ models.

You would need to check this with StoneTaskin, and check the firmware actually does 4096x2304 instead of UHD 3840x2160:

StoneTaskin New 4K R9516 Universal HDR Freesync EDP VBO 144Hz DP1.2 LC

1st. product description R9516 is a LCD monitor driver board that can support UHD. Products support VGA, SVGA, XGA, SXGA, uxga, QHD and UHD resolution TFT LCD screens, such as LG, Philips, Samsung, AUO and other brands of UHD LCD. 2nd. Product Features 2.0 supports hdr10 high dynamic...

stonetaskin.com

Edit: I see you've already noticed s previous post using this board with a 2017 4K iMac:

https://forums.macrumors.com/threads/diy-5k-monitor-success.2253100/page-27?post=32318774#post-32318774

 

[shijan]

Just discovered that DELL U2725QE use same MediaTek MT9801 chip as JRY boards

 

[shijan]

And newest LG 27G850A 4K 240Hz monitor use newest MediaTek MT9810 chip. So i guess future versions of JRY boards may also use this MT9810 chip.

 

[Mowgli10L]

I am just about to embark on this (having done 3 x 27" conversions). I assume your R9513 doesn't have USB-C and thus doesn't support charging the laptop? I am considering using a cable like this that allows you to inject PD charging:

USB C to Displayport 1.4 + Type C Female Power Supply Video Cable 8K@60HZ 2m

Take your DisplayPort further with this video cable. Features: USB-C/Thunderbolt Male to DisplayPort 1.2 Male with USB-C Female for Power Supply Aluminium alloy housing Gold-plated connectors Supports up to 8K@60Hz, 4K@30Hz, 100W Dynamic HDR Tonal enhancer, with HDR support, more vivid colours...

www.innov8wholesale.com

I figure if I use a 19 or 20v PSU with a step-down converter to 12v for the board, I can inject a full 65w into the USB-C line. Any thoughts?

As you say, my R9513 doesnt have USB-c input. There are 2 DP and 2 HDMI ports.

 

[jorycz]

@jorycz
The old R1811 V3 board takes a switched 12V source from the 5 pin PH socket to the left in your picture.
From Right to Left in your pic the voltage is +++–– on each pin.

I don't think the connector is on the correct pins in this stock photo, but I've tested there is switched 12V there.
It's Left to Right +++–– in this picture, and it looks like it's on pins 2 and 3, which are both +ve.
The red and black wires are also reversed...
It's the backlight driver circuit, so not a good idea to take too much power from this socket. 😉

https://stonetaskin.com/cdn/shop/products/DIY-5K-universal-R1811-V-4-Driver-Board-USB-C-Freesync-EDP-DP1-4-Compatible-for_1b68cdfa-99c4-474c-acac-eed0db3da6ed.jpg

That 5 pin PH socket of V4 seems to be the same. 3 pins + and 2 - / GND (clearly marked on the back) and switched so when board goes to sleep, this 12V also go to around 0.4V which is perfect.
Btw with 180 Ohm resistor stock fan is completely silent and today I connected W1209 and attached probe directly to heatsink to eliminate this resistor in case of higher temperature and it works perfectly. Temperature is around 34°C after 30 minutes but it will go higher I think.
I'll do more testing tomorrow, connect similar probe for Noctua PWM fan using this controller and that should be all for this build of first iMac Display.

 

[ricknot]

Does anyone have the pin outs for the small control board for the on screen menu and power switch? I think power is pins 2 and 3 or 2 and 3 from the top of the cable on the 1811 board but want to make sure. If not I can get the multimeter out I guess. Thanks.

 

[PaulD-UK]

@ricknot A pic from earlier in the thread. 😉

 

[ricknot]

Thanks but my board is different. It looks like this.

 

[PaulD-UK]

@ricknot Then you don't have a R1811 board, you have a JRY-W9CUHD-AA1 board.

These are the power switch connections:

It's all listed in this post:

https://forums.macrumors.com/threads/diy-5k-monitor-success.2253100/post-33447926

 

[ricknot]

@ricknot Then you don't have a R1811 board, you have a JRY-W9CUHD-AA1 board.

These are the power switch connections:

View attachment 2516643

It's all listed in this post:

https://forums.macrumors.com/threads/diy-5k-monitor-success.2253100/post-33447926

Yes you are correct! Thanks so much. I am going to connect in the iMac power switch to the cable rather than soldering to the board. Wish me luck.

 

[balika011]

From @SubDriver (24 May 2025)
Converting iMac 5K Retina Display to a Standalone 5K Display

________

_____

Video Inputs (Resolution/Hz/bit depth) ​

____

_____

____

_______

Controller Board	Input Voltage​	HDMI Ports (Protocol)​	DisplayPorts (Protocol)​	USB C (PD Watts)​	Audio Amps​	Driver Chip​	Chip Maker​	USB-A / B Ports (Version)​
R9A18 V1 (Note 4)	12 Vdc​	2 (2.0) (5 (4K/60/8)​	2 (1.2) (5K/60/10)​	None​	10 W​	RTD2718Q​	RealTek​	None​
R9A18 V1.1 (Note 4)	12 Vdc​	2 (2.0) (4K/60/8)​	2 (1.4) (5K/60/10)​	None​	10 W​	RTD2718Q​	RealTek​	None​

The R9A18 V1 uses an RTD2797UPM chip. This is why it needs two dp cables and has external dram.

 

[jorycz]

After the whole day using brightness between 80-90%, heatsink temperature stabilized between 37 and 38 °C depending on the weather, which is currently around 23 °C. I’m curious about hot summer days but I think 180 Ohm resistor will be still OK. I set full cooling when temperature reach 41°C+.

 

[ricknot]

I have my jry-w9cuhd-aa1 up and running and in glorious 5K. I had a hiccup now and then but with the forums help it's working. My only issue is that the daughter board isn't working. I have the iMac power with wired into 1&4 and it turns on and off like a charm. The other switches are not working at all. Menu won't come on. Any ideas?

 

[sunxkui]

I bought a 27MD5KL driver board with a problematic speaker, paired it with a LM270QQ2_SPAS3 LCD panel for about 1800-2200C NY To Taobao, and DIYed a 5K monitor.

 

[PaulD-UK]

@ricknot If you have disconnected wire 4 from the Control Strip when you connected it to the iMac’s power switch then that would stop all the other buttons working.


Wire 4 is the common Ground negative connection for the whole Control Strip. It needs to be connected to the pin 4 of the strip as well as to the iMac power switch.

 

[ItsAShaunParty]

Hi Everyone!
I was digging through the thread for information and got a bit frustrated, so I decided to create a custom GPT trained on the first 111 pages of this thread to see if it would help. I haven’t used it much yet—it’s a little rough around the edges—but it can be useful. You can ask it to link directly to specific posts, including ones with images and build details.

I’ll probably take it down in a few days, but I figured some of you might find it helpful in the meantime.

Here’s the custom GPT on ChatGPT, based on the first 111 pages of this thread. I think you need a free ChatGPT account. I apologize if it acts weird or makes things up!

ChatGPT - DIY 5K Monitor GPT

DIY 5k Thread at Macrumors - First 114 Pages!

chatgpt.com

Let me know if you use it and how it worked. I'm pretty curious.

 

[PaulD-UK]

Haha. Good addition to the thread, rated 7/10.
Basic recommendations are fine, some of the nitty gritty details are a bit off, and it doesn't go into fine enough detail to give a definitive answer to a specific question.

Also it seems to give equal weight to posts in the thread where a user has got settings wrong , and the posts explaining how things work best...

So if anyone is going to use it, it will save a lot of search time.
But check here with a post to confirm ChatGPT has got it right, it doesn't always.

 

[ricknot]

@ricknot If you have disconnected wire 4 from the Control Strip when you connected it to the iMac’s power switch then that would stop all the other buttons working.


Wire 4 is the common Ground negative connection for the whole Control Strip. It needs to be connected to the pin 4 of the strip as well as to the iMac power switch.

Doh!!! I see more soldering in my future! That was a stupid mistake. I swear I know what ground is and its importance.

 

[SubDriver]

Hi Everyone!
I was digging through the thread for information and got a bit frustrated, so I decided to create a custom GPT trained on the first 111 pages of this thread to see if it would help. I haven’t used it much yet—it’s a little rough around the edges—but it can be useful. You can ask it to link directly to specific posts, including ones with images and build details.

I’ll probably take it down in a few days, but I figured some of you might find it helpful in the meantime.

Here’s the custom GPT on ChatGPT, based on the first 111 pages of this thread. I think you need a free ChatGPT account. I apologize if it acts weird or makes things up!

ChatGPT - DIY 5K Monitor GPT

DIY 5k Thread at Macrumors - First 114 Pages!

chatgpt.com

Let me know if you use it and how it worked. I'm pretty curious.

That's an outstanding idea! Like @PaulD-UK said and as you recognize, it has its rough spots.

Is there a way to maybe constrain the inputs to focus only on the details in Post #1 and the pages and additional websites that are identified in Post #1? (I am still a ChatGPT noob). I think that would probably result in a 90-95% solution with information that has been selected and curated by many of those who have contributed the most to this thread (like @PaulD-UK ).

 

[balika011]

The R9A18 V1 uses an RTD2797UPM chip. This is why it needs two dp cables and has external dram.

FIY:
The Razer Raptor 27 144Hz uses the same chip.
The the 165Hz one uses an RTD2717Q.
I'll be looking into flashing the 144Hz version to make it drive it other panels.
The firmware source code is easy to find for LR6410 die. (RTD2797PM / RTD2797UPM )
Ofc we need to modify it to match the pcbs.
Sadly i can find any source code for RTD2717Q / RTD2718Q / RTD2719.

Did you guys know that the RTD2718Q also have vga input, just not wired?

Also: Did you know that the I2S (spdif / toshlink) can be found on testpads on R9A18 board?

 

[ItsAShaunParty]

That's an outstanding idea! Like @PaulD-UK said and as you recognize, it has its rough spots.

Is there a way to maybe constrain the inputs to focus only on the details in Post #1 and the pages and additional websites that are identified in Post #1? (I am still a ChatGPT noob). I think that would probably result in a 90-95% solution with information that has been selected and curated by many of those who have contributed the most to this thread (like @PaulD-UK ).

It was having a lot of trouble linking to posts at first. For some reason, it would link to random threads. I think it was due ot some specifics in the forum URL format. It still has some trouble with proper linking.

I suppose I could try to have it discern for itself which posts to emphasize. Part of the problem is that I exported the thread in a text document with links to images. The document is a mess. And I think it sees it that way. I wish there were a better way to read the thread. It would likely pick up on the relevant posts and contributors.

Update:
Using my GPT....

ChatGPT - DIY 5K Monitor GPT

DIY 5k Thread at Macrumors - First 114 Pages!

chatgpt.com

So this is kind of cool. I asked, "If I want to use audio too, which board should I get?"

It answered:

If audio is important in your DIY 5K monitor build, here are the best controller boards to consider based on built-in audio amplifier power and features:

🔊 Top Boards for Audio Use:​

1. R1811 V.4
   • Audio Amp: 10W
   • USB-C PD: Yes (65W)
   • Pros: Strong audio output, full 5K@60Hz support, and USB-C power delivery.
   • Note: Some users find its fan noisy—modding or replacing it with a Noctua is common.
2. R9A18 V1 / V1.1
   • Audio Amp: 10W
   • USB-C PD: No
   • Pros: Still good audio output, slightly simpler board.
   • Note: Requires dual DP cables for full 10-bit color depth at 5K.
3. Haijing T95MV (SG95MW)
   • Audio Amp: 10W
   • USB-C PD: Yes (60W)
   • Note: 4K board only—do not use this for a 5K build.
4. Haijing T18 / T19
   • Audio Amp: 5W
   • T18 supports USB-C PD, T19 doesn’t.
5. U49
   • Audio Amp: 8W
   • USB-C PD: Yes (65W)
   • Note: Only 5K@30Hz via HDMI—not ideal for smooth video.

🛠 For Re-Using iMac Speakers:​

• You will need crossovers to separate tweeter and woofer signals.
  • Option A: Buy adjustable crossover boards.
  • Option B: DIY with capacitors/inductors inline.
• iMac speakers are 4 ohm, so ensure compatibility.

✅ Recommendation:​

For best overall results, go with the R1811 V.4. It combines:

• Best audio power (10W amp)
• USB-C power delivery
• Support for 5K@60Hz@10-bit via a single DP 1.4
• Multiple input options

Just be prepared to address the fan noise if you're sensitive to it.


Let me know if you need help sourcing it or planning speaker wiring!

---- Not bad!

 

[balika011]

RTD2718Q Official pinout:

RTD2718Q Pinout from reference design board ("DEMO_A_V01"):

Official specs:
2x DisplayPort 1.4 input
2x HDMI 2.1 input
1x 16 lane V-by-1 output
1x 8 lane eDP output

Actual specs:
3x DisplayPort 1.4 input
2x HDMI 2.1 input
1x VGA input
1x 16 lane V-by-1 output
2x 8 lane eDP output
1x DisplayPort 1.4 output

As far as I can tell RTD2717Q, RTD2718Q and RTD2719 are the exact same chip with no differences at all.
There are two twisted pair pins that i wasn't able to identify yet.
They aren't used on any of the DEMO boards and I don't have the source code for the firmware (yet).
There is a Chinese seller asking 60K CNY for the source. That's too much for me to pay.

 

[balika011]

@PaulD-UK It looks like i can't edit the first post. Can you please fix the chips listed there?

 

[Jack2010]

I can't believe the price... is it any good for "our" purposes?

https://www.aliexpress.com/item/1005006686862336.html

 

[PaulD-UK]

@Jack2010
On the previous page of this thread @gul1ver posted 'Used a crossover at a low price on AliExpress, the sound is not very good.'
His crossover is not the same - it's for both channels, but it is similar.
They are copies of designs for use in cars etc, with 8 ohm speakers, driven at much higher levels...

The inductors on these cheap crossovers is for a much bigger bass speaker, and the capacitors for the tweeter are too small, so reduce the mid-high frequencies too much.