Quieting down the Cisco SG200 POE Switch

So this weekend someone asked me about an issue they had with the Cisco POE switch being very noisy. He sent me this link he found where a SysAdmin went and found replacement fan’s for his switch to quiet them down. http://wahlnetwork.com/2014/12/21/diy-project-replacing-stock-cisco-sg300-52-fans-silence/
The fan’s currently in the switch are: https://www.digikey.com/product-detail/en/delta-electronics/EFB0412MD-R00/603-1581-ND/2560704
He suggested if this fan would work as a replacement: https://www.digikey.com/product-detail/en/ebm-papst-inc/412-2/381-2459-ND/592230
After a brief look into the datasheet, I found that the current fan vs. the new fan did not have a “Tach” to read PWM to get a return value on how fast the fan is moving, it did, however, have a Stop Rotation Detection method through the third wire. In this case, the replacement fan he suggested would spur a large number of false positives for error’s as the line should only go HIGH when the fan is jammed verses every 1/10000 of a second for its speed. So I instead dug through my box to locate an L7808CV Positive 8V voltage regulator. I found 8V make’s the fan extremely quiet and kicks the speed down. I ended up testing it with my bench variable power supply before concluding the 8V was the value I wanted. I quickly threw together a board and hot-snotted the unit to the back of the SG200 and what do you know, quiet as a ninja and no fan alerts.
 
 
 

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