Viako Mini Letter ML-45 LEAP E-350 Barebones Nettop

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Fan Control & Acoustics

The BIOS of the Giada motherboard used in the ML-45 offered a few different fan control options for both the CPU and System fan. Either fan could be set to full speed, manual (static), or automatic.

Automatic fan control options.

Automatic mode can be configured with the starting speed (a duty cycle value between 0 and 255), the slope of the curve (how fast the speed increases), and the temperatures at which the fan starts/stops. The default settings had the System fan at full speed and the CPU fan starting at a value of 140. After playing around with system for a few hours we found that it remained adequately cooled without any fan speed increases over the stock settings, so we made only one adjustment: changing the CPU fan mode to manual and leaving at its starting value.

SpeedFan with correlations entered.

Windows users have the option of using SpeedFan to control both fans. Changing the IT8721F chip's PWM 2 mode value from "ON/OFF" to "Software controlled" in the Advanced menu allows full voltage control over the two fan headers using the Speed04 and Speed05 controls. Unfortunately SpeedFan lacked a CPU temperature sensor so for that other software such as Core Temp is required.

System Noise
CPU Fan Speed
System Fan Speed
SPL @0.6m
20~21 dBA
23 dBA
33 dBA
Ambient noise level: 10~11 dBA.

Without any fans turned on the system (or rather the hard drive, being the only component with moving parts turned on) measured 20~21 [email protected] Our chosen fan control settings resulted in a measurement of 23 [email protected], which means it effectively doubled the noise level. The System fan was drowned out by the CPU fan despite running at 100% speed so we can understand why full on was its default setting. By comparison the CPU fan at full speed brought the noise level to an earsplitting 33 [email protected]

The ML-45 with a Seagate Momentus XT installed measured 22~23 [email protected] using our custom fan settings.

Using our custom settings the fan acoustics were excellent, surprisingly soft given the size of the fans in question; tiny 40 mm models tend to be particularly whiny and tonal but no such affects were noticeable at this level. While we didn't have any complaints regarding the fans, the noise generated by the ML-45 was poor because it suffered from some horrific and random coil whine. In a quiet environment it was easy to pick out the high pitched squeaks and squeals coming from the voltage regulation circuitry of the CPU/motherboard. In the graph above it seemed to manifest at the >10 KHz where there's a spike of about -5 dB. The coil whine would stop briefly from time to time, but only went away when turned off, put to sleep, or put on a heavy load.

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