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cannot get same resolution on my screens
I have a latitude 7390 with Intel UHD card connected to a TB16 (K16A) dock. I have two 27 inches screen, a HP Envy 27S connect to mDP, and a Dell U2718Q connected to HDMI.
I can get 3840x2160 or 2560x1440 on the HP screen and only 1920x1080 at 30Hz on the Dell screen which looks really bad, how is it and is there anything I can do about it?
jphughan
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March 7th, 2019 06:00
First, are those the ONLY two displays you have connected to the TB16? The TB16 can do dual 4K displays, but that's it. If you're trying to run those plus a third display, you won't have enough bandwidth to do anything very useful on the third display.
If that's not the issue, try connecting the UP2718Q over the full-size DisplayPort output instead of HDMI. The reason is that according to the Display Resolution Table on Page 22 of the TB16 manual here, the HDMI output can only do 4K up to 30 Hz, so you really wouldn't want to use that anyway. It's also possible that the UP2718Q doesn't accept 4K 60 Hz on its HDMI input, since that requires HDMI 2.0, which is relatively new. Not all displays accept their maximum resolution and refresh rate on all of their inputs, simply because HDMI is typically a few years behind DisplayPort in terms of max resolution/refresh support. I admit I can't explain why your setup is falling all the way down to 1080p 30 Hz even if that were the case (again assuming you're not running three displays from the TB16), but switching to DisplayPort is worthwhile anyway.
If that doesn't fix it, try updating the following, in this order:
- System BIOS
- System Thunderbolt 3 drivers/software
- System Thunderbolt 3 controller firmware (not part of the BIOS update)
- TB16 firmware
- Intel graphics driver
If even that doesn't fix it, just as a test, does the UP2718Q run as expected if you disconnect the HP display?
Thomas Vit
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March 7th, 2019 07:00
Thanks for the valuable input. I do confirm I only attached 2 monitors only, not 3.
I will try your suggestion and use a DP cable instead of the mDP one and see if that makes adifference.
Regarding the update sequence, I need to check, I found a firmware upgrade tool on Dell Support (https://www.dell.com/support/home/us/en/04/drivers/driversdetails?driverid=7tj1h) and I used Dell command update to upgrade the rest, on ething i noticed is that new Thunderbolt software generates a warning at each boot:Device was approved during boot, but is not part of the current approved devices list.
Thomas Vit
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March 7th, 2019 10:00
jphughan
Thank you! I tried the DP cable and now my 2 screens are at 3840x2160 60p Hz
Problem solved
jphughan
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March 7th, 2019 11:00
I believe that happens if you have the Thunderbolt boot support options enabled in your BIOS, since that causes devices to be allowed to connect even if you haven't approved them. The reason that Thunderbolt systems default to requiring approval is because Thunderbolt grants access to PCIe, which means a device can gain direct access to everything in your RAM. That can obviously be a security concern, since it would allow a malicious device to steal things like decryption keys that might be in your RAM at the time. Anyway, you might be able to get rid of that message by starting your system with the dock disconnected and then connecting it only after Windows completely loads. At that point you might see a prompt to approve the newly attached Thunderbolt device, in which case choose "Always allow". Good luck!