A thermal module less than half a millimeter in thickness. No fans. Thinner. Lighter. That's the Lenovo ThinkPad Helix for you. It's been a few months since the Helix convertible tablet was refreshed with Intel's Broadwell processor, otherwise known as Core M (the same processor used in Lenovo's Yoga 3 Pro), and the benefit is that it runs cooler than ever. So cool it might not even need a fan.
While we're not 100% on the supposed fanless-ness of the Yoga 3 Pro, the ThinkPad Helix is touted very much as being a fan-free design (as the video above would indicate). The thermal module is, in essence, a blade of a heat sink, pulling heat from the Broadwell processor and dumping it onto the perimeter of the device. It's just runs cool enough that you don't necessarily need a fan to manage it.
Source: Lenovo (YouTube)