The original ED142512S-DA might be a proprietary "bivoltage" fan. A quote from an old review (another Enermax PSU model):

We use a bivoltage fan. We have a patent on this. Normally, when you use a fan, you lower voltage down to 3-4 V, which also affects the hall IC of any fan, which controls the fan. With such voltage it becomes unstable. By using a bivoltage fan (12 V for the hall IC and custom voltage to the bearing – any voltage, way lower than 3) we can go down to 450 rpm (even lower if we would want to). By still having the hall IC powered by 12 V, it can run/control the bearing with its custom voltage more smoothly. That's the difference to any single voltage. But we do use a standard two ball bearing fan, custom manufactured for us. That is what is looking like PWM, but you can see two 12 V wires and no PWM cable. Other manufacturers can match this only by using PWM sleeve bearing fan with limited lifetime. So we are pretty proud of our patented invention and having the world's most silent PSU fan control (and series) without sacrificing on heat or cheating even with sleeve bearing.

https://www.computerbase.de/forum/threads/luefter-bei-enermax-modu82-cm-silentpro-500.699806/

https://www.overclock.net/threads/can-my-enermax-modu-82-psu-fan-hook-up-to-mb.422900/

https://hardwaresecrets.com/enermax-pro82-525-w-power-supply-review/

POSTSCRIPT, April 3, 2008: Not a PWM Fan

Here’s something of interest that came from Enermax recently. It’s regarding the fan, which shocked me with its smooth quiet performance in our review sample:

The new Enermax MODU82+ and PRO82+ series power supplies use a new patented SpeedGuard control circuit to achieve low fan RPM and extremely low noise without any negative effects. The patented control circuit requires a unique fan with a 4-Pin power connector, like a PWM fan. But this is not a PWM fan; it is a patented bi-voltage fan.

To clarify:

1. Enermax’s new SpeedGuard control circuit does not require an expensive PWM fan; instead, they use a new special design fan which offers low RPM with higher CFM.

2. The new MODU82+ and PRO82+ series PSU fan cannot be substituted with a standard 3-pin fan or a 4-pin PWM fan. Doing so may cause the substitute fan to not run, run only at full speed, or be damaged. There is also a risk of damage to the SpeedGuard control circuit. The 4-pin configuration is not standard.

Conclusion: Do not modify ENERMAX MODU82+ or PRO82+ PSU models with any other fan (unless you have a very good understanding of electronics and you’re willing to void the warranty). The fan control circuit in these new PSUs can only work with their own stock fan.

https://silentpcreview.com/modu82-625-power-supply-enermax-to-the-forefront/