Journey to a Silent MicroATX Gamer

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PRELIMINARY MEASUREMENTS

It is standard SPCR protocol to establish baselines by measuring the noise of a system before it's even turned on. Fans, specifically, are run to establish their range of noise. In this case, since both the VGA and CPU cooling devices/fans could be altered during development, just the Corsair Air 240 fans were measured, mounted in their default chassis locations. The fan in the Seasonic G 550 power supply had zero impact on the measured or heard noise during this test.

Corsair Carbide Air 240
Noise Baseline
All Fans
RPM
SPL @1m
12V
1550
33 dBA
9V
1250
29 dBA
7V
1070
24 dBA
5V
700
18 dBA
4.1V
540
15.5 dBA
Measuring mic positioned 1m at diagonal angle left/front of case.
Ambient noise level 10~11 [email protected]

The three fans sound quite similar to the Corsair Air AF120 Performance Edition we reviewed in 2013. The differences are small: A little less rubber in the damping sleeve at the mounting holes, and a rating of 0.3A compared to 0.33A in the Air AF120. Like its retail cousin, the Air 240 case fan retains a slightly buzzy quality at higher speed and some rattling/clicking at low speed. It's not a great sound fan, but run slow enough, it should be OK.

The minimum 15.5 [email protected] SPL obtained with all three fans going as slowly as possible without stalling is a bit daunting. It is higher than we'd like. But fans can be swapped out if necessary.


The fan used in the Corsair Carbide Air 240 is a slight variant of the Corsair Air AF120 Performance Edition.

TEST & ANALYSIS TOOLS

The OS used is Microsoft Windows 7 Ultimate, 64-bit. We have yet to be sold on any version of Windows 8 on a desktop system.

Conditions throughout testing: 21~23°C temperature, 11~12 dBA background noise.

For the record, CPU and GPU manufacturers have cautioned that Furmark and Prime95 are extreme stress applications that no real software, including games, come close to emulating. The key issue here is extremely high AND continuous load. Real games and apps have ups and downs in power demand. Often not large, but they are there. In contrast, the amount of up and down we observe with either of these stress programs is typically 1% or less. We use Furmark because it's relatively fast and two threads of Prime95 run simultaneously is a pretty good simulation of how a real game loads a CPU. We have tried playing games with the systems we build in these guides; they rarely hit more than 85% of the power load observed under Furmark + Prime95.

CONFIG 1

The first system configuration consisted of the following:

  • Intel Core i5-4690K
  • Gigabyte Z97MX Gaming 5 motherboard
  • Zotac GTX 970
  • Noctua NH-D9L dual-tower 92mm fan
  • Kingston HyperX Genesis 4GB x2 RAM
  • Crucial MX100 512GB SSD
  • Seasonic G 550W

The PCIe power cables to the Zotac GTX 970 card had to be bent over and pushed back for the side cover to go on. It was a tight fit, with the cables pressing up against the clear acrylic window.

The stock fans were kept in their original positions: Two intakes in front, one exhaust on top rear. The fan in the Noctua NH-D9L CPU cooler was oriented to exhaust its heat up, straight toward the top mounted case exhaust fan.

Total AC power draw with Furmark + Prime95x2 peaked around 270W.

Zotac's utility for the GTX 970 had very little to offer, so I immediately tried the now-familiar ASUS GPU Tweak, which thankfully worked to control the Zotac VGA fans without any problems.

This configuration was a failure. The base SPL was around 20 [email protected], and under load, there was no way to keep the Zotac GTX 970 fans from hitting the nVidia hard-coded >90°C full speed fail-safe. Not without speeding up the case fans to the point where the whole system was always too loud; ie, over 30 [email protected] On top of it all, the CPU temperature easily jumped 15°C whever the GPU was loaded up. The case fans simply can't seem to move the heat quickly enough out of the case to keep this from happening.


One AIDA64 sensor screen capture of many similarly poor temperature results with this configuration. Note the CPU fan RPM; it's not quiet at this speed. Ramping the case fans up to full speed was really the only way to keep both CPU and GPU down.

I tried rotating the case so that it lay on its right side. This is one of the Corsair-approved positions for the case. There was little if any difference in either thermal or aural performance. This is confirmation that the rubber feet affixed on the bottom are tall enough not to cause additional impedance to airflow.

There seemed to be three interrelated issues:

  • The Zotac GTX 970 cooler can't cool the GPU at load without running its fans at pretty high speed.
  • The case fans can't evacuate hot air fast enough to keep the CPU from being affected by the GPU heat.
  • The CPU cooler can't cope with both CPU heat and the additional heat from the nearby GPU.

Other than the nCase M1, the 15 liter space for the main components in the Air 240 case is the smallest we've tried in our Gaming PC Guide series thus far. The Rosewill Legacy W1, for example, has a main compartment volume of 23~24 liters, despite its smaller m-ITX only format. In the much smaller space of the Air 240, I'm trying to quietly cool some 230~240W of heat with smaller heatsinks and fans. No surprises. Time to bring in bigger guns.



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