12v cooling fan.

[InspectorJon]

I got a computer case cooling fan to run inside my fermentation chamber I’m putting together. It is a 12v fan, specs say 10.8-13.3v. What will happen if I connect it to an old 16v laptop power supply? Run fast, wear out bearing, . . . Poof?

 

[IslandLizard]

A 20% overvoltage...

You could test it using that power supply and measure the actual clamp voltage, If it drops to 14V or below, probably all good.
If not, use:

• a serial resistor (of ample wattage)
• an LM317 circuit to reduce the voltage
• or use one of those $4 PWM DC speed controllers off eBay/China.