0x00 Reasoning⌗

The price of the 1 gigabyte router become lower and lower recently, especially for used Cisco routers. The big company retire them and sell them at a cheap price. I got Cisco 2921 for only 50$ including shipping fee and tax. It is a good deal when the 1 gigabytes home router requires more than 50$ in the US.

0x01 Problem⌗

Every story begins with a “however”. This router has never been designed to be used in bedrooms: 4 high-speed industry fans have been installed in the front of the router. It sounds like a Jet. Nobody can sleep in this environment. A solution must be found.

0x02 Solution⌗

There are several solutions.

The first solution is returning 2921 router and changing for a fan-less and lower-end model – 1921. Nevertheless, due to the fact of no noise, the demand of that model is higher than 2921, causing a higher price. Also, this model does not come with VoIP feature, which may be useful.

Since it is irrational to spend more money on a lower-end model, it is better to modify 2921 model.

0x03 Plan⌗

The plan is relatively easy: disassemble the router; remove the high-speed fan; replace them with low-speed but quieter fans.

The fan I chose is “quite 6”. It is the only option for 60mm fan other than “Noctua.” 9$ each for 4, 38$ in total (they cost almost as same as the router, but I can reuse those fans for everything else I want. Also, it is much cheaper than “Noctua” fans)

I do not want to destroy the connector of the expansive fans, so I spent 6 more bucks on the fans connector (Amazon is robbing me!!!).

0x04 Some details⌗

Connect the fan male pins to the connector on the router. Note: the blue wire is used to control the speed of fans. The quiet 6 does not support speed control, so I just leave it open.

Here is the final work.

0x05 Testing⌗

This router was designed to be used with a high load, but the situation in my room is lighter. The low-speed fans should be able to get things done. After running the router with DHCP service for 2 days, the highest temperature never goes over 52 Celsius, which is good.

The sound is definitely lower than before; however, the chassis of the router created a good sound chamber, making some noise louder than fan itself. My roommate gave me a good suggestion which is put the router into the drawers. After that, the sound is lower than the dehumidifier in the room, which is totally acceptable.

Router>show env all
...
SYSTEM FAN STATUS
=================
 Fan 1 OK, Medium speed setting
 Fan 2 OK, Medium speed setting                                                 
 Fan 3 OK, Medium speed setting                                                 
 Fan 4 OK, Medium speed setting                                                 
                                                                                
SYSTEM TEMPERATURE STATUS                                                       
=========================                                                       
 Intake Left temperature: 29 Celsius, Normal                                    
 Intake Right temperature: 26 Celsius, Normal                                   
 Exhaust Left temperature: 35 Celsius, Normal                                   
 Exhaust Right temperature: 30 Celsius, Normal                                  
 CPU temperature: 51 Celsius, Normal                                            
 Power Supply Unit temperature: 31 Celsius, Normal  
...