Thermals, power consumption, noise
The Zotac OI520 is a cool customer, which is no surprise thanks to the 22nm Haswell processor with a 15W TDP. Under prolonged full load, the CPU temperature can hit 60-65 degrees Celsius, but that’s really not a realistic scenario, since very few people will run demanding applications or games on such a system.
The Core i5-4200U is relatively powerful and doesn’t have to break a sweat in everyday tasks such as browsing, office applications and media consumption. In that case the CPU temperature will usually hovers in the 35-40 degree range, depending on ambient temperature, which is excellent. Unlike underpowered Atoms, Celerons and low-end AMD APUs, the Core i5 simply doesn’t have to work hard most of the time, resulting in less heat, less noise and practically no throttling.
PCMark 8 indicates the Core i5 does not have to work hard and operate on peak Turbo clocks too often
This also reflects on the power consumption – it’s extremely low and shouldn’t go over 30W under load, staying south of the 9W mark when idling. It can go up by a couple of watts if you add more hardware or use one of the four USB 3.0 ports for an external hard drive, but that’s about it. The Sphere needs as much power as a cheap two-bulb lamp from IKEA.
We already pointed out that this is the quietest actively cooled ZBOX PC we ever tested. Thanks to its relatively large volume and shape, the Sphere acts as a muffler. In normal use it is practically inaudible and even under full load it’s difficult to hear the fan, even in a quiet room. Unfortunately we had no access to professional grade audio equipment, but a few basic tests revealed that idle noise ranges from 31-33db. Better yet, it barely goes up under load, staying under 35db at all times. Many small systems quickly leap from 30db to 40+db under load.