I recently got back into 3D printing and purchased a CR-10 from GearBest.
Everything has been working good but it was too loud and I wanted to make it more quiet. The main things creating the noise were the fans and the stepper motors. In order to fix this I replaced the noisy fans and added stepper motor dampeners.
I mainly followed this blog (needs to be translated to English) and this YouTube video explaining how to install the dampeners.
Add stepper motor dampaners to the X, Y, and Extruder stepper motors
Replaces the fan at the back of the control box
Replaces the fan at the front of the hotend
Replaces the fan in the center of the control box
Replaces the fan in the power supply