External monitor black during boot/only picks up Windows

Hi, I have a Dell XPS 17 9710 connected to a Dell UP2720Q external monitor via a Thunderbolt cable. The XPS remains powered on with the lid closed and with the UP2720Q displaying Windows. The issue is that whenever I boot the monitor does not detect a thunderbolt signal coming from the XPS and briefly enters standby mode until Windows desktop shows up without porblems. So whenever I need to enter BIOS or any other pre Windows activity (booting from an external USB drive), I am forced to use the XPS internal display. Is there a way to have the external monitor pick up the thunderbolt signal at all times during boot? I explored BIOS setting and enabled an option called "Allow thunderbolt boot devices" or something like that without success. Thanks

If you want to see display messages on an external monitor at BIOS level you have to press a key combination after bios loads. On my Dell I tap f2 for 5 or 6 sec at boot which puts the computer into bios even though I can't see it. I then hit FN+F1 and the bios screen shows on external monitor. If that key combination doesn't work try just F1.

antares said:

Is there a way to have the external monitor pick up the thunderbolt signal at all times during boot? I explored BIOS setting and enabled an option called "Allow thunderbolt boot devices" or something like that without success. Thanks

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Have you tried updating the drivers from Dell?
There are some very new drivers released for the NVIDIA GeForce RTX 3060 (December 2021) and Thunderbolt 4 port controller (November 2021).

Download from this page. Better still click on the "Let Dell automatically find drivers for your XPS 17 9710" :

(-- The page link I have provided you is set to UK. You may need to change your location in the top right corner of the webpage to your region --)

iko22 said:

Have you tried updating the drivers from Dell?

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Yes, all my drivers are updated. But drivers are loaded with Windows, so AFAIK they have no effect during POST. And my issue is that the monitor is black during POST.

This is not a driver issue. It is by design. The bios for your motherboard may use a different key combination to make the switch at bios level.

antares said:

Yes, all my drivers are updated. But drivers are loaded with Windows, so AFAIK they have no effect during POST. And my issue is that the monitor is black during POST.

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Have you tried each of the 4 TB ports?

I ahve a monitor and a TV hooked to my RTX 2070.
In order for me to see "both" the BIOS splash screen and the Windows loading screen on my monitor, I have to use one specific DP connector on my vid card (it has 3).
If I use either of the other DP connectors for the monitor, I will only see the Windows loading screen, on the monitor.
The BIOS splash screen will show on the TV (HDMI).

The point here is that not all connectors from a graphics part, are set to the same priorities.



If I hook the DELL monitor to either of the DP connectors marked with BLUE dot, my BIOS splash screen will show on the TV.
When the DELL is hooked to the GREEN DP, then I will see both the BIOS screen and the Windows loading screen ON the DELL monitor.







In other words... I would imagine that not all your TB ports behave the same way.
I looked up the XPS 17 specs... it said this...

Ports
4 Thunderbolt™ 4 ports


It could be that none of them will give you the BIOS splash screen on your external monitor.
But I would make sure to check ALL of them.

antares said:

And my issue is that the monitor is black during POST.

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Just a tip - is the display USB thunderbolt connection connected to the left-hand side of the Dell XPS 17 9710? According to Dell, the XPS 17 9710 gives priority to devices plugged onto the left-hand side and it is recommended to plug displays into the left ports. Check your cabling and let us know how you get on.

Hi Ghot and iko, according to the User Guide, Dell recommends connecting the external monitor's thunderbolt cable to the left hand side ports of the laptop, and that's exactly how I connected the monitor to my XPS 9710, using the left-hand side port. I did not test the other 3 thunderbolt ports, but I would assume that all of them would behave the same way during POST, i.e., not delivering any signal. I can surely test that too, but thing as they are I think that the best solution would be a BIOS firmware that would include a setting to unlock thunderbolt during POST.
Glasskuter, will surely try pressing either F1 or F4 after F2, but the problem here is that my external keyboard/mouse is also connected to the thunderbolt port, and if there's no signal coming out from any thunderbolt port during POST that would also mean that not only the external monitor but the external keyboard is also dead during POST

antares said:

either F1 or F4 after F2

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No, it's a combination of keys FN+F1 AFTER the bios has had time to load. I found that solution on the Dell forum. It was also suggested if that key combination did not work, to try just F1. Since the splash screen to enter bios appears for such a short time frame (and you can't see it) start tapping F2 5 or 6 times as soon as you hit the power button.
The user guide for XPS shows the first external monitor on the BACK left side port.

antares said:

if there's no signal coming out from any thunderbolt port during POST that would also mean that not only the external monitor but the external keyboard is also dead during POST

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Are you using an external mouse and keyboard? The LED lights on these devices should flash on and off during POST. If not try disconnecting them and using the internal keyboard and mouse.
Also, what is the make/model of USB docking station you are using?
Can you get external display working after the Boot sequence?

iko, I don't have any USB docking station. My setup is very simple: external monitor directly connected to the XPS via thunderbolt, as well as external mouse and keyboard (Logitech USB unified receiver plugged in to a USBC to USB2 adapter)

antares said:

iko, I don't have any USB docking station. My setup is very simple: external monitor directly connected to the XPS via thunderbolt, as well as external mouse and keyboard (Logitech USB unified receiver plugged in to a USBC to USB2 adapter)

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Are you using the cable supplied by Dell, to connect the monitor?
Make sure the thunderbolt cable is plugged into the 90W connection on the monitor (ie, not the 15W).

iko22 said:

Are you using the cable supplied by Dell, to connect the monitor?
Make sure the thunderbolt cable is plugged into the 90W connection on the monitor (ie, not the 15W).

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Yes of course, I'm following the monitor's instructions to the letter.