The switch

The Linksys SD2008 has great specs: it provides 8 10/100/1000 Ethernet ports. All ports have auto speed and duplex negotiation, auto-MDI/MDI-X and a true non-blocking fabric so in theory one can run line rate traffic accross all ports simultaneously.

The switch is incredibly tiny, cold to touch (metal casing) and generally comes accross as a very desirable piece of kit.

My plan is to install a couple of those at home to wire my walls with Cat6 Ethernet and have a few RJ45 available throughout the appartment. Gigabit made sense because the switch was very cheap. In my view it would be a mistake to spend $25 less and get a 10/100 only. Modern computers tend to have Gigabit ports built-in now, so there was my opportunity to jump on the bandwagon.

Noise problems

To my dismay, the switch produced terrible fan noise when plugged in. Keeping it on my desk was rapidly no longer an option. I can work in front of a humming Sun workstation 8 hours a day, but this latest addition to my desk made the noise level unbearable. Searching the web I came accross various posts suggesting that this was a trend with this product line.

I contacted Linksys technical support regarding this issue, and got the following answer: "The SD2008 is not designed to be used in a living-room. Usually, people don't need a gigabit connection for their personnal use. The switch is maybe a bit noisy, but we can not help you for this issue." Not much appreciation of my problem here, but I did not anticipate anything different.

Some took the issue lightly but didn't provide otherwise reasonable explanations or suggestions.

Other people reported that in their case there were two Sunon 40mm fans (6500 rpm, 30 dB) inside, which were successfully replaced with 21 dB models (this may have been in a previous hardware revision of the switch). Unfortunately, no pictures or explanations were provided to open the case, other than "The front pops off, allowing the top and bottom to slide apart."

Opening the SD2008

Without waiting further let's see how to open this unit and exhibit the fan.

The back can be removed by pulling back and tilting the plate up/down at the same time.

The front pops off easilly once the back has been removed.

The metal casing is made of two assembly which slide into each other.

The inside is revealed. The fan assembly in particular is what we're interested in and it sits on top, blowing directly on the naked components.

The motherboard is accessible once the fan is removed. The two main components are two Broadcom ASICs. The central asic onboard the Linksys SD2008 switch is a Broadcom 5388 which has 8 MAC and 4 PHY subsystems. So this is the switch backplane where all the logic takes place. The other 4 PHY (I presume wired to ports 5-8) are on a Broadcom 5464. The two big components at the bottom of the pictures are Bothhand G4P109 gigabit magnetics.

But let's get back to our fan assembly which can be unscrewed and separated from the motherboard.

The motherboard is unscrewed from the chassis.

Let's apply some power and enjoy the sweet silence.

The BCM5388 product brief mentions "fanless operation supported" and the BCM5464 product brief mentions "requires no airflow or heatsink". With this in mind, we should be able to find an appropriate replacement for the annoying fan.

Onto Part 2: Replacing the Fan >>
Onto Part 3: Performance Testing >>

gaetan@soltesz.net