2 options.
1. make something like this [www.thingiverse.com] and slow them with your controller.
2. supply them with a different voltage. If your using an atx supply connecting the + from the fan to 12v and - to 5 gives you 7 volts. Slows fans nicely but still work (most of the time). If not using an atx supply then there are many simple variable voltage circuilts available using very cheap parts.
1. make something like this [www.thingiverse.com] and slow them with your controller.
2. supply them with a different voltage. If your using an atx supply connecting the + from the fan to 12v and - to 5 gives you 7 volts. Slows fans nicely but still work (most of the time). If not using an atx supply then there are many simple variable voltage circuilts available using very cheap parts.
