Quote from: 100knot2dae on December 02, 2022, 02:48:00 PM

The cooler fan in my batch 1 standard unit also never goes below 1800 RPM. Has anybody made good experience with replacing the stock fan with a Noctua NF-A8 PWM or a NF-R8 redux-1800 PWM yet on the Apollos? These should be able to turn at least as low as 325 RPM.

Working on it!

But it is a 92mm fan that is required.

The contraption shown in the photo has a Noctua 200mm fan on top, a Noctua NF-A9 PWM where the stock fan used to be, a Duratech Precision 80mm Silent Case Fan 12V 0.08A 1600rpm YX-2570 on top of the power supply, and the stock power supply fan is throttled down with a 500ohm trimpot until I cannot hear it any more.

It's whisper-quiet when I turn on the added fans, but the Noctua NF-A9 PWM lacks power when I run it by itself.

In 24-25degC air temperature, with 'Auto cooling' equivalent settings for the standard Apollo, running in turbo mode, the ASICs temp gets to 79degC while the Noctua fan runs at 1924rpm.

That means the fan is almost maxed out (max speed is 2000rpm) and it will not cope with much hotter ambient air temperature once summer comes around properly.

That said (and stressing again that I do NOT recommend replacing the stock Apollo fan with the Noctua NF-A9 PWM), it is much quieter than the stock fan when operating in conjunction with the auxiliary fans.
It is also much quieter than the stock fan when it is running by itself (auxiliary fans turned off), but the ASICs are a lot hotter, 79C vs 60C. That cannot be good for their life expectancy.

And the Noctua NF-A9 PWM will not cope by itself if ambient temperatures get into the toasty range.