The system top cover will become hot if the LCD is closed when external monitors, mouse, and keyboard are attached to the USB 3.0 Dock.
The above symptom is associated with, but not limited to, the following systems:
Helix (Type 3XXX)
System is configured with:
Systems that have a USB 3.0 Dock attached
If the Helix (Type 3xxx) LCD is closed to allow for external display using the Lenovo USB 3.0 dock, the flap covering cooling fans should be left open to allow for adequate cooling.
Below is a picture of the flap open, on the top cover, to allow air circulation.