Brand new Mac Studio, 2 identical brand new Samsung monitors connected via USB-C. Every log in is an adventure with the screen assignments. My $2,000 machine cannot remember where I designate each screen. What's up with that?
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
Re: Preaching to the choir.
We're not preaching to anyone, we're having a discussion. Clearly a number of users who are having this issue HAVE contacted Apple support and shared that info with the rest of us. That's what communities do..
And it's thanks to user DIGITALBRENT sharing his experience around this issue that I now use his hack to correct the issue when it arises.
After trying everything else I have found that Digitalbrent's hack of putting the Mac Studio to sleep and then instantly clicking or moving the mouse to wake it again seems to work. Just to clarify, if your Mac Studio wakes and your displays are mis-configured, simply put the Mac to sleep and instantly wake it again and for some reason your displays will reset to your original configuration. ( WTF Don't ask me ).
That is not currently supported. But if you wish to make that suggestion, here is the page for that:
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OK, so I'm going to ignore the idea that it's not Apple's problem. The last update to Monterey was to address this problem on the mac mini. If I had a toothbrush in my mouth and another up my butt I'd know which was which..
However, I may have found a work around. Whenever I leave my desk for a while I select LOCK SCREEN from the apple menu. So far this seems to work.
Do you have these monitors daisy chained or plugged into two separate ports. Daisy chaining does not wrk.
This morning's boot up went fine. The displays showed up in the correct orientation. Again, this is with the Studio Display in the middle and two 4K Samsung displays of different vintage to the left and right. Now, the Samsung displays have different names. Now, one is "U28E510" and the other is "U28E590". I think the latter is the newer one. Previously, using two displays of identical vintage , the names showed up as "U28E510(1)" and "U28E510(2)". My conclusion is that it helps to have screens with different names.
Another thing: previously, with the two Samsung displays both named "U23E510", the dock used to hop around from display to display on reboots or awakening from sleep. That has not happened using one "U23E510" and one "U23E590".
I've been fortunate because my office has several displays with identical specs to choose from.
I'll report again if this seemingly-happy resolution is not stable.
The Mac sends a query to the display whenever the connected displays MAY have changed.
This query is only sent at certain times:
• at startup
• at wake from sleep — so momentarily sleeping and waking your Mac may work
• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go
• on invoking Option-(Detect Display) button in Displays preferences (from another display)
Waking from sleep is a time when The Mac is not certain what displays are still connected, so it ASKs. But these Samsung displays LIE TO IT.
I changed to this configuration because of a different problem. Previously I had one connected via HDMI and the other via a USB to HDMI dongle. I found that the HDMI port initialised much faster than the USB-connected one, so when the system woke from sleep, for a short period before the other one woke up it thought it only had one monitor. Unfortunately this period was long enough for macOS to move all my windows onto the first monitor.
That problem went away with both connected by USB, but now I have this problem instead.
Clearly while Samsung shouldn't be reusing serial numbers, macOS knows which port the monitors are plugged into, so identifying them with something like a hash based on serial and port would be reliable enough, but they're apparently not doing that either, or even ignore the serial number altogether. I found a bunch of other reports showing that duplicate serial numbers are common across many different monitor manufacturers, giving all the more reason for Apple to fix or at least work around it.
as I said above:
a) get Samsung to put the display serial number in the correct field in the EDID message sent to the Mac -OR-
b) don't use twin displays that have this issue.
Further to my note above: following the lead suggested by Grant, I located another Samsung 27" 4K display in the office. This other display was purchased in a different year than the two described above. It looks and behaves the same and has the same specs. Using this one in place of one of the ones that was getting confused, is a step forward. In preferences/displays, in the arrangement panel, now the two Samsung displays have different names. This may improve behavior.
Just a heads up that non of the above actually worked. However, Apple has just updated Monterey this morning on my machine and one of the fixes was the system not recognising a second monitor connected to a USB C port.
Let's hope this fixes the problem..
When you post here, you are "preaching to the choir". Readers are all other users like you. Apple movers and shakers do not come here looking for things to do -- they are already busy.
You can leave feedback here:
You can open a support "ticket" here:
or you can contact the display maker and let them know you will need to send back their inferior displays unless you get a firmware upgrade that fixes this.
That may be true, but it's a useless and aggressively unhelpful comment. Duplicate EDID serials appear to be common across major manufacturers, and they don't exactly say "uses a duplicate serial number" on the box. The practical reality is that Windows and my 10-year Old Mac Pro don't have a problem with them, and it's something that Apple could easily provide a workaround for in macOS.
Apple shipping a minor tweak in an operating system update is an awful lot easier than forcing expensive, wasteful upgrades on an installed base of millions of monitors. Apple also has a history of doing exactly this, as they did to fix the dire video port problems with M1 Minis when they were launched.
I have a similar problem. Apple Studio Ultra, top of the line. 12.3.1. One Apple Studio Display in the center, and two Samsung 27" displays with 4K to the left and right of it. The Samsung displays are a few years old but never misbehaved on my Mac Pro. "Every log in is an adventure"... true. I have to go back to display preferences and rearrange the screens so my cursor will track correctly left to right after almost every startup ... and sometimes after a mere sleep as well. Every display is on its own rear Thunderbolt port. I've tried rearranging what ports are used for what screen, but to no avail. My $7000 machine cannot remember where I designate each screen... what's up with that?
So, that lasted for about a day. Just been for dinner, returned and the screens gone weird again. The second monitor didn't even come on!
So, I'm trying this next. I've de-selected all the options in mission control
I'll try this option and see how long it lasts. It might not be suitable for your use but I don't have a problem with this set up..
That's interesting, I knew others were having this problem.
HOWEVER, let's suppose for a moment that the EDID meant that the mac studio couldn't tell which display was which, and so, on restarting or logging back on, the display arrangement was occasionally switched. Bearing in mind that I have one display connected to the HDMI port and the other to a USB-C port. I could probably live with that. It would be a pain, but hopefully APPLE would fix the issue at some point.
BUT, the fact is, even though I have both displays on exactly the same settings, whenever I log off or restart the chances are that not only will the displays be switched around but the resolution will be reset. And, AND sometimes the secondary display won't even come on. I have to reconnect it to get it to work.
For me this is an issue with Mac OS Monterey. The latest update fixed a similar issue with the mac mini..
How do I make my Studio remember which monitor is which?
