The relevant part of my system is straightforward - a Radeon R9 370 card with HDMI + DisplayPort output. The monitor is a 4K (3840 x 2160) Dell UltraSharp UP3216Q with HDMI 2.0 and DisplayPort connectors.
My solution is to move to a pass-through EDID emulator to solve this properly. The intended effect is that if I turn the monitor off but the cable is still connected, Windows will see it (due to the emulator) as still connected, and windows won't move round. But if the cable itself is unplugged, the EDID emulator will be disconnected with it and Windows will see a change of monitor or loss of monitor instead, which is ideal behaviour. That should fix it, if the EDID emulator works as expected.
Important point to note: The EDID emulator needs to be a "pass through" type - one that has male and female ports, "listens" to the monitor's own EDID, and remembers/emulates it when the monitor isn't powered on. "Headless", "dummy" or "ghost" EDID emulators are the wrong type. Those types are used to fake a monitor totally, to a computer that doesn't have any monitor at all, so that the graphics card will be fully used in calculations and remote desktop work. A headless/dummy EDID emulator only have one port, a bit like a USB stick, and won't do the job I need; it needs to be pass-through.
My proposed solution is to notice that my monitor has HDMI 2.0 as well as DisplayPort. That means I could feed it 3840 x 2160 on the HDMI port and use an HDMI EDID emulator instead. Unlike DisplayPort, I'm pretty sure that 3840 x 2160 HDMI pass-through EDID emulators are much easier to find on the market and cheaper too, and this would solve my Windows problem equally well.
Will an HDMI EDID pass-through emulator work correctly "behind" a DP to HDMI adapter?
Can DP to HDMI adapters, and HDMI EDID emulators be found, that work at 3840 x 2160 @ 60 Hz? 2. Will HDMI 2.0 handle it? Are all adapters/emulators pretty much equally reliable for this kind of need, or should I go for a specific buty more expensive brand?
If it'll work, what would be a recommendation for the cheapest "known good" adapter and emulator I should get?
I'm in the UK and usually buy on Amazon or EBay.
Chaining worked, but I had to check with the manufacturer for model numbers and to confirm it would work. Their tech team kindly tested it for me, to check that the HDMI EDID adapter would work behind a DP to HDMI adapter, and told me the exact parts they had used to make it work.
The parts I used were from Lindy, and were a 41068 DP1.2 to HDMI 4k 60Hz converter, with a 32113 HDMI 2.0 EDID adapter plugged into it. Initially I got the adapter the wrong way round - be careful if you use these parts, the "male" (plug) end of the HDMI EDID adapter faces the computer, the "female" (socket) end faces the monitor.
Obviously there are probably other people making these; at this time there isn't much choice but that's likely to change.
They're working absolutely fine, rock solid, on both my HD TV and my 4k monitor.
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