XPS 9550 - Trouble with external monitor 4K@60Hz

My new XPS 15 9550 does not seem to support external monitors in 4K@60Hz correctly.

I have updated all of the drivers and BIOS to the very latest files available on the Dell support page, including the newest Thunderbolt 3 driver and firmware.

I have managed to connect the laptop to the monitor (4k@60Hz) using a usb-c/tb3 to displayport adapter (kiwibird's). It works (and image is fine), however when the monitor goes to standby, it's almost impossible to wake it up again (I have to unplug the monitor, turn it off, turn it on again, and plug it again...).

When the laptop is connected to the same monitor using hdmi ports (1.4), I am not experiencing any trouble (wake up does work), but I'm stuck at 4k@30hz (as expected).

I have contacted Kiwibird support, they've told me the standby issue is a known issue related to the Dell's thunderbolt 3 driver when Dell XPS 15 (9550) is connected with 4K monitor. I have not found a confirmation so far (on the forums) that it's indeed a software issue, and I'm still wondering if the adapter is working correctly.

Any thoughts ?

Maybe another cable and/or adapter brand, either DP or HDMI, is working correctly (4k@60hz and standby/wakeup works) ?

Thanks
tranb3r

 

Did you ever get any resolution on this issue?

 

Yes: use the official hdmi2.0 adapter from dell.