Sealed??? How does that work? The only way it can run fanless is
with good ventilation.

Sure you can, several of the newer home theatre types of PCs use extended
heat sinks to dissipate the heat from their CPU, video and I/O chipsets. So
while that particular case and motherboard might not lend itself to such a
setup, it's certainly "possible" to do it. But that doesn't change the fact
that unless you're planning on a helm installation it's often cheaper to
just buy two used laptops instead.