Production Noctua 40mm 20mm width fan for ENP-7660b and fx600
- Thread starter Otamot
- Start date
just sorted it for youWho bought all the black ones?It says on pre-order now. I managed to get hold of one, but had planned to get two...
Is the Noctua fan you use to replace the stock fan the 5V or 12V model? In the fan swap guide it says 5V on it but the stock fan is 12V...?
Well spotted yes 5Vdc is used, with loads no more than 500W.
Why 5V instead of 12V. Very simply a 40mm noctua fan doesn't have sufficient airflow to cool ENP-7660B under high loads. Also the startup voltage of a Noctua 12V fan is high, around 6.5V. The fan voltage mapping of ENP-7660B means it sits at around 3Vdc to around 480W. So a 12V noc would not spin up at all until thermals reach a point where it comes on. If the load is not near the PSU limit it should cool the PSU sufficiently to move the fan map back down to 3Vdc and so it would cycle on/off. That also then causes the power supply to run much hotter leaving higher residual thermals in the system. The problem is the bearing tech used in Noctua, their fluid bearings can't do high rpms that a dual ball bearing can and that's what limits the max airflow.
Running a 5V with restricted load means we actually end up with a cooler running power supply against stock as at 60% duty cycle (3/5) as opposed to stock which runs at 25% duty cycle (3/12). In a simple linear comparison you'll calculate you get a fraction more cfm from a Noctua running at 60% duty cycle compared to the stock ADDA fan or Yate Loon (which has less cfm than the ADDA fan) - For small form factor this means less heat left radiating into the system.
In short Silverstone FX600 will run hotter than ENP-7660B as the Yate Loon used in the silverstone runs at a lower rpm and has less airflow and although the airflow should be similar between Adda and 5V Noctua, we found the Noctua runs the PSU cooler than the Adda.
What happens to the 5V Noctua when load goes above 480W though? Will it not break when the voltage goes too much above its rated voltage?
it shortens the fan life. takes about 1-2 months, according to Noctua, ie if you were to run it at 12V constantly.
But it doesn't suddenly kill it.
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