Multiple monitors with a Windows desktop

[Donald]

I have asked a similar question before but we have upgraded some hardware. So I felt a new thread would be appropriate..

Recent desktop with DisplayPort built-in and two HDMI ports on a card.

The DisplayPort has a DisplayPort to HDMI adapter plugged into it and the main monitor is connected to the HDMI side of that adapter. .

One HDMI port (on the card) is connected to a HDMI to SDI adapter which goes to an ATEM and the other HDMI port is connected to a 4 way HDMI splitter that goes to four TV monitors on the walls.

The problem is at times the PC's main display screen shows up on the TV monitors on the walls or the ATEM as it's main display.

My guess is Windows is not finding its main monitor powered up on the DisplayPort and so it tries to find another monitor to use.

We need this to be more reliable as multiple people use this setup from week to week.

My assumption is if everything besides the desktop PC is powered up first, then Windows will always use the previous setup for display 1/2/3 when it's powered up? True?

Curious question, does Windows only look as far as one of the adapters to be operational or does it need to see the device beyond the adapter to make sure it can use it as a monitor? My guess is for the display port adapter it needs to see see the actual monitor powered on. But for the HDMI to SDI and 4 way HDMI splitter, seeing that device powered up is all the is needed. Does not to see a power up SDI device (HDMI to SDI) or a wall TV monitors (4 way HDMI splitter).

 

[Donald]

So reading a little on this topic it seems the first priority will be a video card and it may have it own rules for priority if it has multiple video ports. After that would be a built-in video port.

As it's going through the ports in priority order it's looking for a port where the device sends back an EDID. HDMI to SDI adapters send back a EDID. Unsure if a 4 way HDMI splitter does. And I doubt if a display port to HDMI sends back an EDID on it own. It would certainly pass through a EDID sent back by a display/monitor.

 

[dogememe]

Windows is generally very, very good about remembering which monitor is which.

However, any time you introduce an active cable, adapter or a splitter (vs a passive cable/adapter) you have the potential for the monitors unique code to not get passed along or to be duplicated. If I remember right it’s called EDID and it contains a unique identifier like the serial number, the supported resolutions, etc.

There are various free utilities that can read this info. Find one and see if each monitor is being identified correctly and uniquely. If not, there’s your problem. If it is, well we can keep working on the issue

If you’re using both onboard graphics and a dedicated video card there is some priority, usually it can be configured in the BIOS/UEFI, but this doesn’t really matter in your case. Maybe the boot screen will be on the wrong display but once the system gets to the login screen Windows should ignore that and remember which monitor is the primary one.

 

[Pew]

When the computer does not see the DP monitor as #1, does the computer assign that monitor a different number or do you have to go into display settings to adjust the screens again?

How often does the computer get rebooted or turned off? If it's turned off, do you guys keep the screens turned on or do you guys turn off the screens too?

Just making sure, the monitor is a computer monitor and not a TV repurposed as a computer monitor?

It sounds like your 4-way HDMI splitter does send EDID info, or at least replicates them well enough to make Windows happy.

DP to HDMI should carry back EDID too. Have you tried a different DP>HDMI converter? I use a bunch of converters at work for users that work fine but no SDI involved and at most 4 monitors with no additional splitters outside of a USBC docking station.

 

[Donald]

When the computer does not see the DP monitor as #1, does the computer assign that monitor a different number or do you have to go into display settings to adjust the screens again?

How often does the computer get rebooted or turned off? If it's turned off, do you guys keep the screens turned on or do you guys turn off the screens too?

Just making sure, the monitor is a computer monitor and not a TV repurposed as a computer monitor?

It sounds like your 4-way HDMI splitter does send EDID info, or at least replicates them well enough to make Windows happy.

DP to HDMI should carry back EDID too. Have you tried a different DP>HDMI converter? I use a bunch of converters at work for users that work fine but no SDI involved and at most 4 monitors with no additional splitters outside of a USBC docking station.

The computer is only used Sunday mornings. So booted up for a few hours and shutdown.

We expect the 4 TV monitors connected to 4 way HDMI splitter to show the same thing. Always

 

[Donald]

Windows is generally very, very good about remembering which monitor is which.

However, any time you introduce an active cable, adapter or a splitter (vs a passive cable/adapter) you have the potential for the monitors unique code to not get passed along or to be duplicated. If I remember right it’s called EDID and it contains a unique identifier like the serial number, the supported resolutions, etc.

There are various free utilities that can read this info. Find one and see if each monitor is being identified correctly and uniquely. If not, there’s your problem. If it is, well we can keep working on the issue

If you’re using both onboard graphics and a dedicated video card there is some priority, usually it can be configured in the BIOS/UEFI, but this doesn’t really matter in your case. Maybe the boot screen will be on the wrong display but once the system gets to the login screen Windows should ignore that and remember which monitor is the primary one.

Unsure if the display port to HDMI adapter is active or passive. Some passive ones just do pin mapping. Active ones have a chip. And other active ones look like they have a third wire (USB) which I assume is to pull power.

 

[Brons2]

I have 3 monitors hooked up to the docking station at my desk at work, 2 display port and 1 HDMI. Sometimes I'll disconnect to go to a meeting and I'll come back and the resolution is all messed up and super awful like 580x768 or something similar. I end up having to reboot to fix it. I just kind of chalk it off to Windows follies. Driver updates have not fixed the behavior. I could have it re-imaged by our support people but I probably won't until it has additional issues.

 

[Pew]

The computer is only used Sunday mornings. So booted up for a few hours and shutdown.

We expect the 4 TV monitors connected to 4 way HDMI splitter to show the same thing. Always

Interesting. Can you take a snip of your display settings? I'm curious what it looks like.

I have 3 monitors hooked up to the docking station at my desk at work, 2 display port and 1 HDMI. Sometimes I'll disconnect to go to a meeting and I'll come back and the resolution is all messed up and super awful like 580x768 or something similar. I end up having to reboot to fix it. I just kind of chalk it off to Windows follies. Driver updates have not fixed the behavior. I could have it re-imaged by our support people but I probably won't until it has additional issues.

That sounds like DisplayPort hot swap detection issues.