The Zotac ZBOX CI660 AnandTech review

Our friend Ganesh from AnandTech takes a look at the most powerful fanless PC from a mainstream brand, and likes it overall. Unfortunately, the coil whine from hell - mentioned in other reviews - is once again noticeable.

"... it does have its share of issues: While the system contains no moving parts, a dull whine can be heard if you were to keep your ears close to the top of the system. In addition, occasional noises similar to the grating of fingernails over the fins of the heat sink could be heard. All said, though Zotac can claim that the system is fanless and passively-cooled, it is not an entirely noiseless system."

Source: AnandTech