Adjusting the recipe

Bitfenix specifications for the Spectre Pro place them at the upper-end of what would be considered silent. They’re rated 18.9 dB(A) for the 120mm, 22.8 db(A) for the 140mm. Put six (6) of the 120mm and three (3) of the 140mm in a full tower chassis with radiators, sit only a couple meters or less from it, and they are noticeably loud. A little north of 30 dB(A) if my calculations are correct, not including turbulence from the radiators.

I knew this from my previous personal build, Beta Orionis (β Ori). That system featured a water-cool assembly with copper tubing also using Bitfenix Spectre Pro fans. Though the fans were easily drowned out by my headphones.

But I wanted to quiet the system. At the time, the only reasonable option I had was undervolting them — running them at less than 12V — and I bought an inexpensive circuit board for that purpose. Hovering the fans at around 9V allowed the system to run virtually inaudible, but I wasn’t entirely comfortable with the temperatures.

And the pursuit of a quiet build led me to building an external radiator box. I’m very nearly there.

In a recent, now abandoned project, I discovered 120mm fans with specifications very similar to the Bitfenix Spectre Pro with two exceptions: slightly better airflow and reduced noise. The Nanoxia Deep Silence 120mm fans are the quietest 120mm fans I found that still provide 60 CFM. The 1300RPM 120mm fans are rated at 14.2 dB(A), and the 1100RPM 140mm fans are rated at 14.4 db(A). Having a not-insignificant number of these fans still won’t be whisper quiet, but they’ll be significantly quieter than the Bitfenix fans.

The two fans on the bottom radiator were not replaced as doing so would require draining and partly dismantling the plumbing. And I forgot to order one additional fan to replace the fan in the drive bays. That will come later, and the bottom fans will be replaced at the next loop maintenance.