The CB91's motherboard
After opening things up, you'll get an unobstructed view of the motherboard and its CPU socket. The PC also comes with a BTX CPU cooler. After checking with Gigabyte, we learned that this barebones unit can also accommodate any full-height BTX cooler.
A BTX form factor SFF PC
New to the BTX concept: Nothing impedes air-flow from the CPU cooler.