It is entirely passively cooled. The GTX 950 has a thermal profile (TDP of 90W [0]. The 350W recommendation is for your entire system, it's not asking you to add 350W to the size of your current power supply. The Airtop can passively cool about 200W, so they put in a GPU at 90W TDP, and a CPU at 85W TDP
[0] http://www.anandtech.com/show/9547/nvidia-launches-geforce-g...