Sure, humans may disagree that 67C (153F) is cool, but it is for a semiconductor. More impressive, it was the temperature recorded on a CPU with a 150W TDP attached to a fanless Noctua NH-D15. Does that mean it was noiseless? Nope. The test kept each of the case fans maxed out at 12V input DC (100%).

This, without the fans.

Hardwareluxx does not specify how much air gets blown across the passive cooler. Their claim is that the case fans just ensure that the ambient temperature is as low as possible. That seems fair, but I could also, for instance, blow cool air through a 3-inch drier hose attached to a bathroom suction fan stuck out the window. That would certainly keep passive coolers chilled while only being technically fanless.

Theoretically, of course. I'm not saying it's something I did in high school or anything…

Depending on how long of a hose is used, it could even be noise in a different location (rather than case fans in the same PC). Still, cooling 150W is a feat in itself. Then again, with over two pounds of heat fins, it makes sense.