I was thinking it might be possible to power 4-wire fans directly from the 13.8V instead of the fan headers so as to preserve headroom (and reduce noise) on the 12V computer rail. The 4-wire spec says no more than 13.2V for the fan supply, but the fan might tolerate 13.6 (the voltage my Subaru produces).
While thinking about this it also occurred to me that since the case fan of this motherboard (Zotac 9300-D-E) is not controlled, it might be possible to tie the PWM control signal from the CPU fan port into a 4-wire case fan PWM input.
Thus both fans (CPU and case) would be powered with 13.8V instead of 12, and all controlled via the PWM signal of the CPU fan port. The tach signals would be routed to the CPU and case fan headers per usual.
Has anyone tried either scheme (13.8V fan power or multi-fan control from a single PWM signal)?
SeeYa! -Jim-
As an example of input voltage tolerance, here is a spec sheet for a top motor fan. Note that the tolerable input voltage is spec'ed as 7 - 13.8.
The 4-wire fan I chose for this experiment is also manufactured by Dynatron (Top Motor), so I suspect it has similar specs though none were stated.
If no one responds in the affirmative to my question, I will post the results once this plays out.
SeeYa! -Jim-
I think you'll be fine. That slight bit of extra voltage shouldn't hurt anything. However, it WILL make the fan faster, and consequently louder. And at its spec limits, some of these fans are REALLY loud (depending on the fan).
I agree. The voltage I will be applying does not exceed the fan manufacturer's spec.
SeeYa! -Jim-
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