Fractal Design Array Mini ITX NAS Case

Cases|Damping
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Test Results: Single Drive

System Measurements
State
Idle
100% CPU Load
System Fan
off
12V
off
12V
SPL@1m
19~20 dBA
21 dBA
21 dBA
21~22 dBA
Core Temp
42°C
39°C
61°C
59°C
HD Temp
35°C
31°C
36°C
31°C
AC Power
33W
33W
68W
65W
Ambient temperature: 21°C.
Ambient noise level: 11 dBA.
CPU fan @7V.

By desktop standards, our test system with a single hard drive was fairly quiet, measuring 19~20 dBA@1m when idling with the system fan off, and only an extra 1~2 dBA with it on. The noise is best described as a gentle mechanical hum. The power supply is the most dominant source of noise, though its tonal elements were less evident when combined with the system's other fans and the hard drive. The PSU fan did speed up when the CPU was placed on load, but the difference in noise level was small. It also produced the occasional high-pitched chirp, but only when idle, when the power draw was below 35W measured from the wall. We attribute this to the power supply as we never experienced this previously with this processor and motherboard combination.

CPU temperatures hovered around 40°C when idle and 60°C on load, which are perfectly acceptable numbers. The system's low speed 140 mm fan made only a minor impact. Our WD Green hard drive also stayed pretty cool at about 35°C without the fan, and 31°C when actively cooled.


The system measured 21 dBA@1m when idling with the CPU fan @7V and the system fan @12V.

Test Results: Multiple Drives

Test Drive Noise
Drive
Vibration
1-10 (10 = no vibration)
Airborne Acoustics @1m
A: WD Green 750GB (5400 RPM)
7
14 dBA
B: Seagate LP 2TB (5900 RPM)
6
14 dBA
C: Seagate DB35.3 250GB (7200 RPM)
6
15~16 dBA

For our multiple drive tests, the WD Caviar Green 750GB was joined by a Seagate LP 2TB and a Seagate DB35.3 250GB, the quietest drives we had on hand. The idle noise level of the LP 2TB is the same as the WD Green, but the DB35.3 is a 7200 RPM model designed for DVRs and produces an extra 1~2 dBA. The Seagates are one step below the WD Green in vibration, a subjective rating generated in accordance with our standard hard drive testing methodology.

System Measurements (Idle)
Drives
A
A+B
A+B+C
SPL@1m
21 dBA
22 dBA
22~23 dBA
CPU Temp
39°C
40°C
42°C
HD Temp
31°C
32°C / 35°C
33 / 37 / 36°C
AC Power
33W
39W
45W
Ambient temperature: 21°C.
Ambient noise level: 11 dBA.
CPU fan @7V, system fan @12V.

The use of multiple drives had only small thermal effects on the system, with minute increases in CPU and hard drive temperatures. The large intake fan, despite its low speed, kept the drives well below 40°C. If you plan to fill all six bays, you will want to keep your coolest drives at the edges as only the center four drives are positioned in the fan's path. A pair of 92 mm fans might have been a better choice as it would provide better coverage.

When we added a second drive, subjectively the system's acoustics did not sound much different though it measured 1 dBA higher. Putting the third drive into the mix made vibration an issue, as we started to hear rhythmic pulsing coming from the system once it was installed. This was pretty much a best case scenario too, as we used the quietest drives at our disposal — a single loud drive may be enough to produce this effect. You can stick to quiet drives likes the WD Caviar Green, Seagate LP and Samsung EcoGreen, but eventually once you have enough drives inside, the case will begin to resonate.


A well placed pad reduced both noise and vibration, more subjectively than the measured 1 dBA drop.

The silicone grommets may help, but they are rather small and cannot overcome the Array's thin, light panels. We found that the top cover was a problem, too, as placing a damped weight on it (like a heavy book) created a marginal improvement in acoustics. After some experimentation, we found the best way to deal with this issue was to place a foam pad on top of the hard drive cage, not to dampen it, but to push against the top cover to create a tighter seal. This tweak resulted in the system noise lowering by one decibel and though we could still hear and feel the vibrations, the resonant sound was less audible.


The system measured 21~22 dBA@1m when idling with three drives and padding on top of the hard drive cage.


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