Chenbro RM24508M3RP5 (RM245 series) fans at mach speed, no slow-down? ideas?


Limp Gawd
Jun 30, 2006
I picked up a Chenbro RM24508M3RP5 rack mount chassis which seemed like a perfect way to build a low-cost storage server with some shucked 14 TB drives. Overall I'm moderately happy with the chassis except for one big issue - the fans are in high gear at all times, in wind turbine territory. Kind of like how a professional server from one of the big boys would sound when it first starts up for a few seconds then ramps down.

Here's a link to the Chenbro site which details the chassis:

The manual is here:

The backplane for my model chassis is on page 50 of the manual and the only means by which I can assume you can control the fans is via the I2C connector - "The backplane includes a 1 x 4 cable connector used as a management interface to the server board." The thing is, most non-server motherboards do not have an I2C connector nor does my Adaptec hardware SAS controller.

Also on page 50 - "The backplane includes four fan connectors used to control and monitor fan speed." Okay, so the backplane can control and monitor the fan speed but it doesn't seem to be controlling or monitoring anything!

I tried emailing Chenbro and they don't respond. I tried calling Chenbro and they don't answer.

Anyone have any ideas?
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