With this one you can use a 92mm fan together with a LM2596 DC-DC stepdown converter, the internal fan connector of the PSU has a voltage of 24 V common fans run with 12 V.
With this cover you can lower the noise of your Ender-3 PSU.
Keep in mind changing something on the printers PSU is killing the warranty and inside the PSU you've to deal with high voltages, if you're not sure what you're doing please stop it.
PSU Cover 92mm Fan LM2596.STL ==> printed without any support, raft, or brim.
Cover LM2596.STL ==> printed with support.