Before choosing an upgrade board, I took a look at both third-party boards and those created by the original manufacturer, Creality.

Creality upgrade boards

Creality offers an upgraded board for under $50 that uses TMC2208 stepper motor drivers instead, eliminating stepper motor noise.

This upgrade effectively reduces the printer's sound output from 48dB to 36dB, with the remaining noise comes from the Ender 3's fans, which are also easy to upgrade.

This is the board I'll be using: the Creality Silent Mainboard (v1.1.5). I chose to go with a Creality-made board as they're reportedly more stable and reliable.

Third-party boards

There are also numerous third-party board upgrades available for the Ender 3. A popular choice is the SKR Mini E3, which uses TMC2209 stepper motor drivers and adds 32-bit support.

Keep in mind, some third-party boards, including the Mini E3, have been reported to have issues—including input errors and power back-feeding. Therefore, third-party boards are less of a direct replacement and may require some troubleshooting. Still, if you're up for the challenge, they're a great upgrade option.