I have an APC baseboard that runs off 24v.
The two fans (2 x 24v @ 0.16A = 7.7W) were a noisy and power-hungry problem. I've got a couple of Noctua fans of the same size, with "almost the same" or "plenty good enough" static pressure and airflow, that take just 12v @ 0.06A (1.4W) and are almost silent. The fan models are AD0824HS-A71GL and Noctua NF-R8 Redux-1800-PWM if it helps, and the case is in a cool environment under low use, where heat is less of an issue than in a datacentre.
Naively I could put the fans in series (2 x 12v = 24v), but as answers to several other questions point out, this is a mistaken approach as they are inductive in nature.
Given that the PCB and the new fans are both well engineered, I'm looking for the cheapest and simplest way to power these fans from the original 24v pins. It doesn't need to be perfect, but I'd like to avoid a constant 1.4W wasted power drain of using 2 x 200R series resistor, one on each, (or 1 x 100R common to both), or constant loss through a zener diode.
What is my simplest/cheapest solution?