My "latest Macs" are a heavily upgraded 2009 Mac Pro (6c CPU, M.2 SSD, USB 3, RX580...) and more recently a 12c 2013 Mac Pro with an eGPU (Vega 56) - both machines with more than enough CPU power, GPU power and RAM for my needs, but I long aspired to upgrade to a nice 5k monitor to replace my aging 30" WQHD monitor which only took dual-link DVI inputs (requiring clunky and expensive adapter on the MP tube).
The LG 5k Ultrafine monitors are relatively pricey and limited to TB3 (and USB-C) inputs so, no really an option for my equipment.
Dell, HP and Philips all used to offer 5k displays which took two DP 1.2 inputs to run at 5k, but they were all quickly discontinued and don't have the best reliability reputation (does the latter explain the former?).
The last option was Iiyama's 5k which appeared to share the same LG Display panel as the iMac and LG monitors and supported 5k with a single DP1.4 input, but with electronics limiting color to 6 bit+FRC and with poor color accuracy reviews. It has recently been EOL'd.
I was about to give up when I started reading reports on DIY 5k monitors made from spare parts sourced from the Internet. I was intrigued and gave it a go. I should warn you that this is a risky enterprise and that you need a bit a faith (you need to source parts from questionable sources without much if any warranty). It also won't be a dirt cheap option - likely much cheaper than a new LG monitor, but still not dirt cheap.
Here is what you need as a minimum:
- A 5k panel - there are only two commonly available such panels: the LG Display LM270QQ1 (the one used in 5k iMac) and LM270QQ2 (used in LG Ultrafines). Essentially the same panel in a slightly different delivery - the iMac version coming glued to a shiny glass front the exact same shape as the iMac screen, the other being a plain rectangular panel (semi-matt from the look of the photos).
- A 5k driving board - again there seems to be essentially two versions of such board: the R9A18 board which has 2 HDMI 2.0 and 2 DP 1.2 inputs (requiring two DP 1.2 cables to run at 5k/60Hz), and the more expensive R1811 board which as 2 HDMI 2.0, 2 DP 1.4 (one being enough for 5k/60Hz) and 1 USB-C input (with 65W PD). Both boards come with all the necessary panel cables and power supply, but you will have to specify which panel to match.
Both the panel and the board are typically found on aliexpress and eBay. I sourced my panel (an iMac LM270QQ1) from a local eBay reseller to avoid taxes and customs charges, but had to order the board from aliexpress as I specifically wanted the newer and less common R1811 allowing the use of a single DP1.4.
Connecting the two isn't difficult (you have to be careful with those flat cables and thin connectors) and is enough to have a working 5K monitor but, without a proper enclosure, the screen isn't terribly rigid and the whole setup a mess with exposed electronics.
From there you have plenty of options I guess, depending on you DIY skills, but I elected to go for a nice and tidy look, and an option not requiring too much messing around with tools. Having bought an iMac panel, the easiest is to purchase an empty 27" iMac housing - the A1419 version for which the LM270QQ1 is designed to be the "drop-in" replacement screen. The housing is large enough to host the driver board (and even the power adapter if you want). You will have to make sure the display and power cables are correctly connected and routed to the outside (most likely through the memory access panel) before you attach the screen with those pesky sticky strips.
Sourcing a new 27" iMac housing spare part is probably not going to be easy, or affordable, but used parts can often be found on eBay - in various conditions but much cheaper. Note that most often than not the housing will come without a stand, which means another challenge to address.
I wanted to be able to control height and tilt of the monitor anyway, so I pursued the VESA mount option. As you may know, the A1419 does not offer any official solution to install a VESA mount if that option was not selected at purchase time, but it turns out that you can easily remove the original stand hinge mechanism (at least when you have an empty housing), use a A1312 stand hinge mechanism instead and then install the Apple VESA kit which was designed for the older 24"and 27" iMacs and Thunderbolt displays (there are third-party options).
So, in addition to the above panel and board, here is what I needed to get a 5k monitor looking like a VESA-mounted iMac:
- An A1419 iMac empty housing
- An A1312 hinge mechanism
- An Apple VESA Mount adapter
I am quite glad with the end result which looks much better than I feared (but cost a bit more than I hoped as well). I will post pictures once I clean up my desk ;-)
5K/60Hz/10 bit works without any problem on a single DP 1.4 cable with the RX580 or Vega 56, the 4K/30Hz/8 bit over HDMI looks surprisingly nice and crisp (150% size in Windows, similar scaling in macOS), not tested USB-C yet. Colors look very nice, the control board on-screen menu offers the options of native/sRGB/AdobeRGB/P3 color spaces, but I have yet to measure and profile the monitor.
Do not hesitate to ask any question!
