New Bios that may address this issue!
Fixes & Enhancements
Improved the system stability
Fixed system may not able to boot with external monitor with lid closed
Fixed USB audio/mouse may be lag while connecting to Dell Thunderbolt Dock (TB15) and Dell Dock (WD15)
Fixed Fan may be noisy while connecting to Dell Thunderbolt Dock (TB15) and Dell Dock (WD15)
- Fixed Bitlocker Malfunction or Keeps Prompting Recovery Key every time reboot
Bad news: While BIOS version 1.2.0 might reduce fan speeds a bit when using USB-C/Thunderbolt with the XPS 15 9550 it does not fix the issue.
Fan speeds are still constantly at 2500 RPM (measured with HWiNFO64) which is still disturbing in moderately quiet environments.
With new bios:
- Fan speed is lower than it was, though still not particularly quiet. Still the loudest thing in the room.
- XPS 15 does now boot with the lid closed instead of hanging. But to get the dock connected USB KB and mouse detected so I could login, I had to unplug and replug the tb15 USB c connector. Unplugging the keyboard or mouse did not get them redetected.
So it is better, but there are still problems.
No solution to fan speeds here after installing the latest bios.
With no USB-C adapter connected and no CPU usage (0-2%), the fans are not running.
When attaching a simple USB-C to USB3 hub (no devices attached to hub) then fans start to run at 2500 rpm after a few second.
It can be observed that the Intel PCH temperature goes from 43-45 to above 50 degrees within seconds and the fans start running at 2500 rpm. After a while the temperature idles at around 55-60 degrees.
When removing the USB-C hub the temperature drops 5 degrees within seconds. The temperature goes back to around 43-45 degrees after a few minutes and the fans eventually stops again.
Seems like someone forgot to a small heat sink somewhere.
So it is currently not possible to use the USB-C port without the fans running. Following the bios upgrade the fan speed might be lower than before. I have not attached USB-C device before upgrading the bios.
I can confirm the issues mentioned above: After updating the Bios and all drivers on April 16th 2016, I encounter the following issues:
It is frustrating that the connection to the Thunderbolt dock is not working better for such a high cost computer and dock!
when i plug in the ac adapter, the fans start running constantly and never stop until i remove the plug.
when running on battery idle the fans keep dead silent!
temp ~30c , bios 1.2
there are countless posts on this issue (eg notebookreview forums).
when will there be a fix??
Dell XPS 9550 i7 6800HQ
USB-C plugged in w/ HMDI 2K monitor, 1 USB mouse, 1 USB keyboard (from hwinfo)
PCH Temp (°C) : 45-50°
CPU and GPU fans : 2500 rpm
USB-C not plugged in (from hwinfo)
PCH Temp (°C) : 25-30°
CPU and GPU fans : 0 rpm
I have bios version 1.2.14, why is there still this bug ?
Any answer here from Dell ?