Lair Of The Multimedia Guru

June 7, 2015

Loongson 3A heat and noise

The Loongson 3A box i have is loud, which was a bit of a surprise to me. Subjectively the noise from its CPU fan is significantly louder than my 2 overclocked 6core i7 boxes together though nowhere near the hurricane level of the powermac.
Originally i had planned to run the box 24/7 or similar and submit results to fate.ffmpeg.org. But for a box standing in my living room the noise level was too high for that.
Obvious solution rip the fan out and stick a less noisy one in,
IMG_9336B
its a standard 60x60x15.5mm fan, i choose the Noctua NF-A6x25 FLX as replacement, i didnt pick the PWM variant because for some reason the 4pin cpu fan connector was unused and the old fan used a 3pin sys fan connector, so it felt safer to me to use the same.
To remove the old fan t he board must be removed, as the screws cant be undone without holding their behind.
IMG_9338B
With the screws and the fan, the heatsink comes off too:
IMG_9339B
The old thermal compound seemed not entirely uniform, part of it looked more solid than the rest. I intended to apply new anyway so that doesnt matter though, with the stuff cleaned off it looked this way:
IMG_9340B
As the noctua fan is thicker the screws cant be put all the way through the fan as they would be too short, putting them only through the bottom part makes them stick out at the bottom of the main board a bit more but there is enough space, ive also slightly bent the outtermost heatsink fins a tiny bit inward so they rest on the rubber part of the fan and added some o rings around the screws for a bit of extra vibration decoupling which was probably useless.
Thats how the result lookes:
IMG_9342B
and theres the old fan:
IMG_9343B

Does it still work ? yes and it still passes fate
What about heat? before /proc/cputemp was between 40 and 42°C and now its between 38 and 41 °C both while running fate.
For noise testing i put a microphone 3cm in front of the closed box (thats far away from all fans). I was too lazy to switch my other boxes off though:

sys-off-spectrum old-spectrum

new-spectrum

Loongson Box switched off Original (AVC) fan New (Noctua) fan
Filed under: FFmpeg,Hardware — Michael @ 3:30

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