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XPS 15 9500: Intermittent signal on 4K DisplayPort 1.2 monitor with left-side USB-C/Thunderbolt ports
I recently bought an XPS 15 9500 (with UHD+ display), and I noticed that when I connect my external 4K 60Hz display to either of the left-side USB-C/Thunderbolt 3 ports (via a USB-C to DisplayPort cable), the monitor flickers on and off, intermittently displaying my desktop, showing "No Signal", or trying (but usually failing) to re-establish the connection. I would describe the behavior as similar to what I'd expect if the cable were faulty/loose. However:
- The monitor works correctly (and maintains a stable connection) when connected to the USB-C port on the right side of the laptop (the one that does not support Thunderbolt 3)
- The monitor works correctly when connected with the same cable to two other laptops (one Mac, one Windows; both Thunderbolt 3), and it works correctly on all ports on those laptops.
- I tried two different USB-C to DisplayPort cables (different brands), and observed identical behavior with both.
- I tried two 4K DisplayPort 1.2 monitors (different brands/sizes), and observed identical behavior with both.
- If I force the monitor into DisplayPort 1.1 mode, the monitor works correctly on the left-side ports. However, DisplayPort 1.1 is limited to 30Hz at 4K, which is not ideal.
- If I leave the monitor in DisplayPort 1.2 mode, decreasing the refresh rate to 30Hz (or decreasing the resolution) does not fix the issue.
- USB devices and the power adapter both work correctly (and stably) when plugged into the left-side USB ports. I do not have any Thunderbolt 3 devices to test the Thunderbolt functionality.
- If I boot into Ubuntu from a USB stick, the monitor seems to work correctly in DisplayPort 1.2 mode at 4K 60Hz, even when connected to the ports on the left side.
Note that in all cases, even though the monitor doesn't have a stable signal, Windows does correctly recognize all of the monitor's available resolutions and refresh rates.
On my XPS 15, I've tried the following:
- Updated the BIOS to the latest version
- Installed all available Windows updates, including manually updating to Windows 10 Version 2004 (the May 2020 update)
- Updated the Intel graphics drivers:
- To the latest version offered by Dell
- To the latest stable version offered by Intel
- To the latest beta version offered by Intel
- Updated the Nvidia graphics drivers to the latest version
- Verified that the Thunderbolt 3 drivers are up to date
- Disabled Thunderbolt 3 in the BIOS
- Attempted to rule out possible sources of electromagnetic interference:
- Tested with and without the power adapter plugged in
- Tested with and without a WiFi connection
- Tested with the WiFI networking device disabled in Device Manager
- Installed the driver offered by the monitor manufacturer to replace the default monitor driver that Windows offers
Does anyone else have the same issue, or does anyone have any other ideas for things to try before I give up and send the laptop back?
jphughan
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14K Posts
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July 26th, 2020 20:00
@ingjald This might be related to the issues that are being reported with the also-new XPS 13 9300. That system is generating all sorts of reports of issues using Thunderbolt peripherals and docks, and a recent BIOS update seems to have completely broken the ability to use certain USB-C to DP and USB-C to HDMI adapters/cables that worked perfectly fine on older BIOS releases. Based on your test results and what you've tried thus far, I'm guessing this is going to be a BIOS or TB3 controller firmware issue that hasn't been fixed yet. So if keeping the display connected to the non-Thunderbolt port on the right isn't an acceptable workaround for you (or you don't want to risk ending up past the return period and putting up with this issue for an indeterminate time), then unfortunately I would consider sending the system back. Sadly there aren't exactly a lot of XPS 15 equivalent systems out there. Its only real competitor in the PC world is the X1 Extreme Gen 2. I did a small comparison of those two systems here if you're interested.
ingjald
5 Posts
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July 26th, 2020 21:00
@jphughan, thanks for your response!
I suspect you may be right. After reading your response, I booted into Ubuntu again, and the monitor did the same thing as it does in Windows—I guess I just got lucky on my previous boot into Ubuntu. I also tried downgrading the BIOS to the only other available version, but the behavior is the same.
That said, I'm curious to see if anyone else has the same issue (or conversely, if anyone doesn't have the same issue). While I don't mind the workaround for now, I can't rule out a hardware issue, and I certainly wouldn't want to find out that it is a hardware problem after the return period has run out.
ingjald
5 Posts
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July 27th, 2020 22:00
I just found another mention of the same issue with the 9500 (on Reddit), so at least I know it's not just me.
ingjald
5 Posts
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July 29th, 2020 17:00
As another update to this, it looks like the problem is much less severe when the charger is plugged into the other left-side USB-C port. Even then, though, the connection to the monitor is not stable.
Again, this all seems consistent with the issue that folks have reported on the XPS 13 9300.
RaphTorres
3 Posts
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October 24th, 2020 06:00
I have the same issue two day old XPS15 9500 i7 Gen 10 plugged this into my two LG 4k monitors using both USB C ports on left side and continually blinks them on and off. Tried using only one monitor on left side port does the same. So left with only using one of the LG monitors on the USB C port right side of laptop and it works fine. So looks like the Thunderbolt ports on left side have the issue.
Dell please get this fixed!
RaphTorres
3 Posts
0
October 24th, 2020 07:00
Just to add to this I found an interesting link posted below, though it does not mention the intermittent issues it does give you a better understanding of why it could be happening.
https://www.dell.com/community/XPS/Connecting-XPS-15-9500-to-4K-monitor/td-p/7674737
RaphTorres
3 Posts
0
October 24th, 2020 14:00
Just to update things I've connected laptop right side USB-C to one of my LG 4K monitors and the left side Thunderbolt USB to my other LG 4K monitor but on this second monitor's menu I disabled the display port 1.2 option in settings. This has stopped it from continually flickering for now.
DELL-Cares
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October 27th, 2020 05:00
Greetings!
We have not heard from you. Hope you got the answers for your query. I will archive this case for now.
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-Pratheepan.
XPS9500
2 Posts
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April 25th, 2021 05:00
I have the same problem using a Dell S2721QS Monitor together with the XPS 9500.
Ports on the left side --> intermittent signal
(better if i use both connectors on the left side, where one is the charging cable. does not solve the problem completely)
Port on the right side --> works fine
I also tried two different USB-C to DisplayPort cables (different brands).
Due to the arrangement on my desk i would like to use the ports on the left side.
What is the solution?
(Latest Bios version and Windows Updates are installed)
ven_
2 Posts
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December 29th, 2021 08:00
I have XPS 9500 and iiyama xub2792uhsu and i have the same situation. In addition, I noticed that the port on the left side works better when the power supply is connected (also on the left side). The picture instantly turns black when the charger is disconnected. Dell do something about it!
Holbourne
1 Message
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March 4th, 2023 04:00
I am experiencing the same problem (XPS 15 9520). To my recollection, the issue was not as bad before the last couple of bios updates. I can now only connect to an external monitor from the right side port. And then only using USB C. The HDMI connection no longer works.