XPS 15 9750, HDMI monitor goes to black

I experienced close to this after upgrading BIOS to 1.17.1, except my HDMI port stopped working altogether.

Posts in this community from April 2019 note that an earlier version of the BIOS killed HDMI functionality. They were able to roll back. Unfortunately, you can't roll back from 1.17.1.

https://www.dell.com/community/XPS/XPS-15-9560-BIOS-1-14-2-breaks-HDMI-port/m-p/7291997?search-action-id=428486141213&search-result-uid=7291997

Thanks @hootguy ! What you describe makes sense. I think this problem started not long after the latest BIOS upgrade. However, every time I try to downgrade de BIOS firmware, the system doesn't let me. The installation fails or is blocked, despite having the downgrade option ticked in the BIOS settings. I currently have installed the horrendous 1.17.1 firmware version... Does this mean there's nothing I can do to go back?

It may be a problem with the output voltage module of the motherboard graphics card.

Thanks for the insight, @xiaomei Is there any way to check that at home? Or should I take the laptop to a technician? 

I was having the flickering issues previously and reverted back to the March 2020 video driver, which may have helped somewhat, but did NOT fix the BLACK SCREEN issue, which is well known.

My main laptop (4k 15") screen goes black a few times a week and I usually have an external usbc monitor connected, but no amount of disconnecting or changing settings will fix it.  

Reverting from the Intel back to the older Dell provided video driver does not fix the BLACK screen issue.

Josh 

Indeed, it doesn't. But it's undoubtedly a BIOS firmware issue. It turns out that after a certain firmware update, there are some features that can't be downgraded if you downgrade the firmware. If you downgrade the firmware, you'll see that it's going to show you that some features couldn't be changed.

My monitor AOC q2577pwq connected via HDMI started to exhibit that problem. I did not have those problems in the past.

I checked and I'm also on BIOS 1.17.1 which I took on Oct 11th

No matter what I try and which display mode I use, it does not fix the problem.

I managed to roll back BIOS to previous 1.16.2 and the versions of sw are now as on the pictures

The problem is still there which makes me think it is either something else i.e. not the BIOS or there something more to it. As someone described earlier, there may be part of the upgrade that are not rolled back.

This is possible as there is numerous fixes for Intel platform in 1.17.1

List is here

https://www.dell.com/support/home/en-uk/drivers/driversdetails?driverid=rgfwj&oscode=wt64a&productcode=xps-15-9570-laptop

I'm getting USB-C to HDMI cable today to see if that resolves the problem and I'll post the results here

I made a mistake in my post. My laptop is Dell XPS 9570 not 9750.

The issue stands though and the BIOS version used was as with original posts.

I purchased USB-C to HDMI cable, connected to the same HDMI monitor input and so far no problem, so it is not a the monitor.

It could still be a sudden failure of the HDMI cable I used, but this is unlikely. Unfortunately I don't have a replacement I could use.

To me it looks like Dell dev's  released another buggy BIOS and QA team let that slip through the net. Again.

I'm a software dev myself and I don't understand how on earth such a basic thing gets missed? Do Dell engineers not use external monitors?

I will stop doing BIOS upgrades as this becomes ridiculous. I would rather live with Intel vulnerability than risk another upgrade which undoubtedly cripple another part of my laptop. I got fooled again and I won't let that happen. It is really poor Support if you install something that should be trusted, improved software, it damages your machine and the you are told you are out of luck because your hardware support has ended. Basically you are on your own with a partially working machine which was caused by their software in the first place!

How is that fair?

I apologise for this rant but this is not the first time I get burnt.

@ivenhov Indeed, it's a BIOS issue. Been there, done that! The USB-C to HDMI cable won't show any problems. I've been using it for around a month now with no problems whatsoever. But the HDMI port... it's dead. It turns out Dell killed it in a BIOS update - some of the changes applied cannot be downgraded. If you try to downgrade the BIOS (I did multiple times), it won't make all the changes necessary. Past certain firmware version (can't remember which one), you simply can't recover HDMI functionality.

@Leborgne I have exactly the same experience as you described, despite being on a different platform XPS 9570.

Roll back to 1.16.2 did not resolve the problem and what worse Fingerprint Reader stopped working and so did Windows Hello login.

For that reason I upgraded to 1.17.1 again.

This fixes Fingerprint Reader but of course HDMI still failing. USB-C is working as expected.

Thanks for your reply and confirmation, much appreciated.

@Leborgne   @ivenhov  Maybe the route to go, is simply ask for RMA.  Meaning, call tech support, explain that your screen goes black often, for no stated reason.  They have you run diags, blah blah.  Finally the problem isn't solved, and you get an RMA number and ship back the unit.  (hopefully this works)  Back at Dell they won't claim the unit is fine, because they already know that it is a well known issue that is hard to track and test.  And maybe you get a new unit?

just ideas

Same problem here. Very frustated after so much time trying to solve the issue.

Finally i bought an USB-C to HDMI cable as a workaround, but this is not the solution for problem caused by DELL itself through the last BIOS update

Same problem.. I used the laptop for 2 yrs without the hdmi problems. Had my mainboard replaced (under warranty) for other reasons.

After replacement re-installed all software and upgraded all drivers, now I'm stuck with the 'monitor goes black and back on' thing.. 

Reading this thread think I better buy a usb-c-2-hdmi converter iso wasting time on it anymore.

Thanks for sharing the knowledge about this!

I'm glad I found this thread as I have been experiencing this exact same problem.  Can anyone recommend an HDMI to Thunderbolt 3 USB-C adapter?