How do I make my Studio remember which monitor is which?

I have fully resolved my issues with my Mac Studio not remembering which monitor is which. As my previous post stated, I am using a CKLau KVM Switch, and this switch has built-in EDID emulation.

The EDID Emulation appears to trick macOS into thinking that the monitors are still physically connected and turned on, even when I am not connected to the active port the Mac is on. I have tested this extensively with putting the Mac Studio to sleep and waking it up the next day, and even fully shutting down and starting up.

Not once did I have to rebuild my desktops (triple 2k monitors), or had any icons move, or have any monitors not waking up. I am getting a full, Triple 2K/1440 @ 144Hz picture and performance with zero issues.

Originally I had an issue with my monitors turning off and on as I said in my previous post, but it wasn't the KVM's fault, it turns out that the three different brands of adapters and cables I tried out all had the exact same issue with supporting a stable signal. When I tried a much cheaper fourth brand of USB-C to HDMI Cables, it solved my issue and now I have a Mac Studio that acts like a normal computer for once.

The good news: I no longer have to rebuild my work environment whenever I wake up my Mac. All monitors will turn on and stay on. All icons remain in place. I don't have to leave my Mac Studio on indefinitely any more. And no more headaches.

The bad news: In order to make my Mac Studio function like a normal computer with multi-monitor support, I had to spend an extra ~$500 on a new KVM Switch, with new USB-C to HDMI Cables just so the Mac will not forget which monitor is which. Another Apple Premium I had to pay.

It took 10 years for me to dial up a KVM/cable combo solution just so my Mac acts normal.

I suppose whatever this KVM Switch is doing, maybe someone can find a cheaper method to keep the Mac tricked, and perhaps finally get some peace. It's clear that EDID Emulation helps with this, at least via HDMI.

For Reference, this is the combo I have that works 100% with my Mac Studio M1 Max solving the "which monitor is which" issue:

CKLau KVM with EDID Emulation: https://smile.amazon.com/dp/B07RSV2WZP

USB-C to HDMI Cables: https://smile.amazon.com/dp/B085HC43Q9

Work Around.  I have found a work around to this problem.  I am not enthusiastic enough to call it a solution but it is holding for me after 4 restarts.  I have 2 identical 27" Samsung monitors and 1 X 32" (Samsung also).   The 2 x 27" kept getting flipped after restarting.  From my reading of the forums the problem is identification.  I am not a brilliant tech guy but I thought okay, common denominators.  The 2 x 27" were both using USB c Cables to HDMI.  On the back of the Mac Studio is a HDMI output.  What if I put one 27" monitor to that HDMI outlet.  Now the Mac can see that this monitor is different.  So I have 

1 X 27” HDMI to Thunderbolt

1 X 27” HDMI to HDMI

1 X 32” HDMI to Thunderbolt

All three monitors now are not identical.   After 4 restarts the settings are holding.  

So if this works can I become an honorary Apple Genius?

For my specific issue related to this, I have mostly solved it with a KVM that has built-in EDID Emulation (CKLau KVM). This emulation allows me to switch ports between PC and Mac without any of these machines believing that the monitors were physically disconnected, and therefor it no longer reassigns screens with different windows or icons.

I believe they make stand-alone EDID Emulator connectors you can try out to see if it helps. However, they are all HDMI and not DisplayPort based (if using DP).

Despite solving the issue with screens being swapped around, Mac Studio still has a major problem: Now when I wake Mac Studio from sleep, it will cause all my monitors to turn off and on every 15 - 30 seconds indefinitely, until I unplug and replug them back into the KVM. This is my second KVM I am trying here so I know it's not the issue, but the Mac Studio is in fact the issue.

To solve the new issue, I simply have to keep my Mac turned on, indefinitely.

No matter what I do, Apple will not allow me to use Macs as part of a KVM setup without major issues. But I think it's clear that a lot of the problems begin with Apple, and their use of USB-C which requires conversion to third party displays. It's almost as if they intentionally made this a problem to force people to use their displays.

I'm having the same problem on a new Mac Studio with two identical Samsung monitors connected via Thunderbolt to DisplayPort cables. They look lovely and run at 144Hz, but switch sides randomly on every wake from sleep. I tracked down how to extract the EDID info, and it's very simple in a terminal:

    ioreg -l | grep EDID

For me this shows my two monitors:

    | |   |   |   "DisplayAttributes" = {"SupportsSuspend"=No,"MaximumRefreshRate"=144,"SupportsActiveOff"=No,"PortID"=32,"ProductAttributes"={"ManufacturerID"="SAM","YearOfManufacture"=2018,"SerialNumber"=810889805,"ProductName"="C27JG5x","AlphanumericSerialNumber"="HTOKC02346","LegacyManufacturerID"=19501,"ProductID"=3928,"WeekOfManufacture"=51},"MaxVerticalImageSize"=34,"MaxHorizontalImageSize"=60,"HasHDMILegacyEDID"=No,"Chromaticity"={"Red"={"X"=44352,"Y"=20736},"Green"={"X"=18048,"Y"=43328},"Blue"={"X"=9984,"Y"=4032}},"DefaultColorSpaceIsSRGB"=No,"NativeFormatHorizontalPixels"=2560,"DefaultWhitePoint"={"X"=20544,"Y"=21568,"Gamma"=144179},"SupportsVariableRefreshRate"=No,"AspectRatio"=15,"MinimumRefreshRate"=50,"WhitePoints"=({"X"=20544,"Y"=21568,"Gamma"=144179}),"PreciseAspectRatio"=115652,"ContinuousFrequencySupport"="None","SupportsStandby"=Yes,"NativeFormatVerticalPixels"=1440}
    | |   |   |   "EDID UUID" = "4C2D580F-0000-0000-331C-0104A53C2278"
    | |   |   |   "DisplayAttributes" = {"SupportsSuspend"=No,"MaximumRefreshRate"=144,"SupportsActiveOff"=No,"PortID"=48,"ProductAttributes"={"ManufacturerID"="SAM","YearOfManufacture"=2018,"SerialNumber"=810889805,"ProductName"="C27JG5x","AlphanumericSerialNumber"="HTOKC02337","LegacyManufacturerID"=19501,"ProductID"=3928,"WeekOfManufacture"=51},"MaxVerticalImageSize"=34,"MaxHorizontalImageSize"=60,"HasHDMILegacyEDID"=No,"Chromaticity"={"Red"={"X"=44352,"Y"=20736},"Green"={"X"=18048,"Y"=43328},"Blue"={"X"=9984,"Y"=4032}},"DefaultColorSpaceIsSRGB"=No,"NativeFormatHorizontalPixels"=2560,"DefaultWhitePoint"={"X"=20544,"Y"=21568,"Gamma"=144179},"SupportsVariableRefreshRate"=No,"AspectRatio"=15,"MinimumRefreshRate"=50,"WhitePoints"=({"X"=20544,"Y"=21568,"Gamma"=144179}),"PreciseAspectRatio"=115652,"ContinuousFrequencySupport"="None","SupportsStandby"=Yes,"NativeFormatVerticalPixels"=1440}
    | |   |   |   "EDID UUID" = "4C2D580F-0000-0000-331C-0104A53C2278"

and you can see that the two monitors produce absolutely identical output – same serial number, same UUID. Samsung needs a slap, or we need a way to anchor monitor ID to physical port – but the port ID is right there in the output, so macOS could tell them apart anyway! So while Samsung shouldn't use duplicate serials, macOS could work around this. Searching for this 810889805 serial number finds several people who apparently have the same one as I do.

I previously had these same monitors connected to a Mac Pro with an RX580, both connected via HDMI, and while they had other issues, they didn't switch sides.

On Friday I completed the third of three calls with Apple Support Tech Brennan, working out of Canada. The calls totaled about 5 hours, of diagnosis, testing configurations, cables, settings, reboots, firmware, etc. My impression was he did a thorough workup. To make a long story short, this is now a "known issue." He and engineering are aware of this thread and cross-referenced threads as above. It appears most likely that a software alteration will be needed in a future release, since the issue is being categorized, I believe, as a flaw that needs to be addressed by engineering. I am not aware of a timeline and do not have direct access to engineering, but the process of interview and feedback and information relay was conducted with energy and efficiency, so we'll see. Surely Apple will recognize that many Studio customers will be looking for a multiple monitor arrangement. Fingers crossed for an early solution. Aloha to all, T.A. Gill; Honolulu

Took me a while to find this thread but was happy to see that I'm not the only one with this problem. My case sounds very similar to yours. I have a brand new mac studio with 3 identical 24inch Sceptre LED monitors. The studio I bought as an upgrade from my 2019 mac mini (which handled the triple monitor configuration with ease by the way - never had a problem with it switching the arrangement).

The studio lacks the ability to keep track of these monitors. Every time I reboot or wake from sleep, the monitors are rearranged into some whacky configuration. I'm contemplating sending it back and just sticking with my mac mini until they have this sorted out.

I have tried every solution proposed on every forum and thread under the sun that deals with this issue. I have found one band-aid solution that seems to kind of work for me but it's less than ideal. Here's what I do: When I wake or reboot the machine, if the monitors are out of order or incorrect configuration, I figured out that if I put the mac to go to sleep and then immediately move the mouse to prevent if from sleeping, it goes back to the correct configuration. Don't know if this will work for everyone, but it's free and it's worth a shot. This is the only thing currently preventing me from sending this thing back. $2200 for a device that can't even remember which port a monitor is plugged into is a waste of money imo.

Like yourself, I have also spent way too many hours on the phone with an Apple Support senior tech (or whatever they call the next level up from your standard run-of-the-mill tech person that you get when you first call in). We were unable to get a solution the first time I called. She made an appointment to follow up with me after she had a chance to speak to engineering. Of course on the second appointment after a lot of back and forth with them blaming my monitor manufacturer for the issue, and me asking them why it is not happening with my older mac if it's the fault of the monitor manufacturer - We finally arrived at the truth - They have no idea what's going on. Essentially, the end result of my conversation was that I'd have to "wait a few months until the new version of the operating system is released". According to Apple Support, "The new OS version MIGHT fix it." MIGHT... No promises. I'm not waiting 5 months on the chance that it MIGHT be fixed. What's even more egregious is that in our first call, I gave them the link to this thread and they read through it, and then still proceeded to try to pass the blame. Everyone here has done a fantastic job at identifying the actual problem and proposing solutions to it, but clearly Apple is not listening.

Long story short, Apple was no help at all. This is a huge oversight on their part. And to the Apple apologist in this thread (we all know who I'm talking about), I know it hurts you to hear it but this is 100% Apple's fault. The common denominator here is the Mac M1 chip (especially the mac studio). You can't really expect us to believe that every monitor manufacturer is to blame, and even if they were, how much cooler would Apple be if they'd just fix the problem for us instead of lazily pointing the finger at monitor manufacturers and telling us to wait until the next OS release for a possible fix? They have an opportunity here to be the heroes and they are absolutely blowing it! As pointed out by the user with the toothbrush analogy earlier in this thread - they could simply write conditional code that says "if the EDID is the same then base the configuration off of the port number that they are plugged into." I don't understand why if my old mac could do it then Apple suddenly deserves a pass for their new tech not being able to do it. There's no excuses for it. There's no way around it. No matter what the Apple sheep say, Apple took two steps back with this mistake. The fact that they continue to advertise that the studio supports up to 5 monitors right out of the box is nothing but a bold-faced lie.

I have already started telling everyone to avoid mac studio if you have identical monitors. This is totally unacceptable to me. Yeah... Despite the band-aid fix that I found for it, I think I'll be sending this back at least until they can get this sorted out. I'm not at all happy with Apple's response to this issue. I shell out significant (for me at least) cash for this thing I expect it to work properly.

There was an issue like this quite a while ago. The essence of the problem was convoluted.

To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. One of the other things typically included in this EDID information is the serial number of each display.

But since most users have PC, not Mac, they simply slam the resolution and refresh settings to whatever they like and let it rip. This does not provide the appropriate feedback to the manufacturers to get the EDID information perfect every time.

In the previous case, investigation found that the display was not providing its serial number in the correct field. Because of that, the Mac could not tell the twin devices apart, and they constantly swapped settings.

The solution has to come from the display maker. Or a work around is to get away from twin displays that are indistinguishable from the point of view of the EDID information they provide.

This is an update to my earlier post. An Apple Studio (Ultra, 64, 8, current OS) uses an Apple Studio Monitor as the center screen, connected via its own port. Two Samsung 27" 4K screens are outboard, left and right, each in its own port, via adaptors. When using two Samsung screens of the model and same year, the two screens presented the same name, and the OS labeled them XXXX(1) and XXXX(2) in the display orientation preference panel. The display orientation became confused on every awake or reboot.

After substituting a same-model but year-newer Samsung screen for one of the outboard screens, the two screens no longer presented the same name; it was like XXXX and XXXY. Since then, the display orientation has remained steady without a single fault; the cursor of course tracks across the three screens as intended.

Unfortunately, there are issues remaining.

A. Dock. Sometimes, the dock, which is supposed to be at the bottom center of the Apple Studio Display, hops to one or the other of the outboard screens. This does not happen every reboot or wake, but perhaps 15% of the time. Opening the dock panel and redesignating its location fixes this... for a while, until it hops again.

B. Assignment of closed desktop files to display. I have placed several files on an outboard screen's desktop. This is to bother me until I file them properly. Sometimes, perhaps 25% of the time at reboot, the location of these files is switched, as between outboard screens, although the display orientation and cursor behavior has not changed. The files do not seem to ever get reassigned to the Apple Studio Display.

C. Assignment of open files to display. If files are left open at shutdown (as one might, to remind oneself what work to start on next time), upon reboot they may not appear on the same screen as they were on at shutdown. This happens most of the time.

These faults are minor, compared to losing display and cursor orientation. They are quickly remedied, and I just live with them. I wish this did not happen. I have no opinion whether the cause of them is the same as discussed in this thread.

None of these faults occurred with two identical, same-year Samsung displays on my old 2010 Mac Pro running 10.14.8, on a 580 with DisplayPort.

I just got off the phone with a senior support person about this issue. I included this thread in the discussion about it.

She read through my thread here ( Mac Studio + LG UltraGear QHD/2k = Worksp… - Apple Community ) with me on the phone and acknowledged this appears to be an issue with my Mac Studio and how it handles the video output.

I narrowed it down to it being an issue with USB-C to DP with my specific setup, on my KVM.

All my other PCs and even Mac Mini (Intel w/eGPU) works fine for all my monitors when the are all using DP to DP cables only.

My Mac Mini will have these monitor issues if I use any USB-C to DP like my Mac Studio, so I know there's something wrong with the method of connecting video, maybe monitor EDID info is not being sent back to the Mac through this connection, and that's why I have to rebuild my work environment each time I wake the Mac up.

Anyway she's calling me back tomorrow evening after an Engineer has a look at this. I was very detailed in my thread so hopefully they'll have all they need.

I do not speak for Apple. Everyone here is another User like you, unless their Avatar is tagged with "Apple Community Specialist".

I am not advocating you use any particular manufacturer's displays. The issue occurs when you use TWIN displays where the manufacturer has deviated from the VESA standard response format.

Your Mac sends a query to the display, and the display is supposed to respond with its name and capabilities (using the current connection), as well as its serial number in the VESA-designated serial number field in the response.

If the display manufacture does not supply the serial number in the correct field, then your TWIN displays are indistinguishable, and the Mac may accidentally shuffle them.

Okay, so I just wanted to post this update. After following the instructions below my monitors seem to be behaving as expected. I have rebooted my Studio a couple of times and also put it into sleep mode to test it and so far it seems to have worked. I'll update again if the monitor switching recurs again.

Just a heads up that when you follow the procedure you may need to reset some other preferences. I had to reset my menu bar and Doc.

Here's the instructions I followed

Click on your Desktop, click Go in the menubar select Go to Folder.

Enter this text,

~/Library/Preferences/com.apple.dock.plist

press Go

A new Finder window will open with the file highlighted,

move the file to the Trash, do not empty it yet.

Restart your mac, the file will be regenerated.

Open System Preferences> Mission Control and make sure that box is unchecked.

If the behaviour of Desktops/ Spaces is now working as you would expect, then delete the file in the Trash.

It's Not Apple's problem.

Your TWIN displays are presenting themselves in their EDID information as the same display. Not similar. EXACTLY the same display. They are not showing different serial numbers in the correct field, and if they did that, this would not be an issue.

Displays from most other makers do not exhibit this problem.

If you did not have the same Model TWIN displays, you would not have this problem either.

as you posted, the serial number field supplied by these TWIN Samsung displays is identical.

UUID is not supplied by the display, MacOS generates it on the fly.

I agree that someone needs to contact Samsung and pressure them to put the serial number in the correct field in their EDID response.

But PC's don't use the EDID information, so there is less market pressure to get it right, unless Users contact Samsung and complain.

I'm behind you 100%. There's no excuse in 2022 for this issue. The EDID thing is just BS. When they released the Studio they didn't say it will support multiple monitors EXCEPT THIS ONE AND THAT ONE. Didn't anyone at Apple test this thing before they released it?

"When I wake or reboot the machine, if the monitors are out of order or incorrect configuration, I figured out that if I put the mac to go to sleep and then immediately move the mouse to prevent if from sleeping, it goes back to the correct configuration "

I've found the same behaviour with my Studio. It was purely by chance, but it went back to the proper configuration when I moved my mouse after sleeping for only a few seconds..

If Readers have been unable to prove solutions and post them in the any postings already made, then Readers simply do not have an acceptable solution for you. These are User-to-User Support Communities, and Apple movers and shakers do not visit here looking for potential issues.

Your next step should be to contact Apple support with your concern, and work through the first responder's scripts and ask to discuss your issue with a specialist. Unless/until you contact Apple support, Apple can not internalize the scale for the problem, and will continue to be slow to respond.

Get Support

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