How to set Monitor Priority Settings for BIOS/POST Time to Match Windows Default Monitor?

[modem]

Here's my scenario: I have an intel i5-10600 based system using a Gigabyte Z590 Aorus master motherboard with an EVGA GeForce GTX 1070 (non-TI) graphics card. The PC has three monitors, 2 x Dell SE2717H/HX and an older Samsung monitor. The monitor configuration is Dell SE2717H - Samsung, Dell SE2717H.

(1) The left Dell monitor is connected to the 1070 by via DP out on the 1070 (DP to DVI adapter connecting DVI to HDMI cable) going to HDMI input on the monitor.

(2) The center Samsung is connected to the 1070 via HDMI output on the 1070 to HDMI input on the monitor itself. However I have a HDMI duplicator connecting the Samsung monitor to a NanoKVM box. Will explain this more in a moment.

(3) The right Dell monitor is connected via a DP to HDMI cable. It's connected to DP out on the 1070 and HDMI input on the monitor.

When the PC is powered on, the right (3) monitor is the default monitor showing the BIOS and POST screens before booting into Windows where the center Samsung becomes the primary monitor. I have the Samsung set as the primary in Windows, but that obviously doesn't affect the BIOS/POST.

I had swapped the right Dell and center Samsung thinking the monitors were dictating the settings, but when I reconnected them, the Samsung was on the right, it still remained the priority monitor during BIOS/POST time. So I reverted those changes.

I followed the EVGA card port priority per this official EVGA page ( https://www.evga.com/support/faq/FAQdetails.aspx?faqid=59560 ) which indicates the following priority of ports:

- DVI
- HDMI
- DisplayPort (middle)
- DisplayPort (far right)
- DisplayPort (far left)

With the DVI port not in use, I verified the center Samsung monitor was on the HDMI port on the 1070. The left Dell monitor was connected to DP (middle) and the right Dell monitor was connected to DP (far right). However during BOOT/POST, the right Dell remained the priority. I created all sorts of combinations of moving the center Samsung to the middle DP port (using DP to HDMI adapter), for the higher priority # and moving the left and right Dell monitors to far right and far left DP ports. However the right Dell monitor remained the BOOT/BIOS priority default.

Why does this even matter??

The reason I'm trying to solve this puzzle is because I recently purchased a NanoKVM PCIe card that gives full BMC access to the BIOS and visuals via HTML5 web interface to pre-Windows boot time. In the event I need to troubleshoot when I'm away from home.

The NanoKVM has an HDMI input port so it can grab the screen and share it via the HTML5 built in portal on it's remote IP access. Because the NanoKVM isn't multi-monitor aware, it's designed to only display the monitor that it's plugged into in the video card so I can see the  boot /BIOS screens and the Windows default monitor. Because there is no HDMI passthrough on the NanoKVM, I purchased a HDMI duplicator/splitter (NOT an extender).  

This HDMI extender connects to the HDMI output on the 1070. My center Samsung monitor is connected to splitter output port #1 with a standard HDMI cable and the NanoKVM is connected to splitter output port #2 with a standard HDMI cable as well.

When I disconnect both Dell monitors and leave this setup connected to HDMI, it works flawlessly. When I connect the left Dell monitor to the above far left DP port on the 1070, the setup still works great as the center Samsung still remains the default/priority. But when I connect the right Dell monitor to the far right DP on the 1070, the right Dell becomes the default/priority monitor during BOOT/POST time.

This results in the NanoKVM not having access to/displaying the contents of the right Dell when it's priority during BOOT time, but once the PC boots into Windows and it's the default monitor/port, the KVM displays that just fine then.

However, this defeats the purpose of needing the KVM which is to provide access to the BIOS and boot menu settings in the event of an emergency while I'm away from home.

Any idea on what I'm doing wrong? Do I need to replace the center Samsung??

Different monitor / adapter cables???

Do I need to upgrade the video card? I have a 980Ti, but per the EVGA docs, the port priority is the same for it as the 1070.

Thoughts?? Suggestions???

[Mindovermaster Global Moderator]

Your BIOS/UEFI doesn't know what your main monitor is set to in Windows. As for the rest, I'm not so sure..