What are my options in replacing the noisy fan in my Linksys Cisco SRW2008P managed GigE switch?

Question

My first managed GigE switch, the Linksys SRW2008, was a dream, until it started randomly chattering on various ports. That started while I was on the road all the time, which made it take forever to diagnose, but that's a different problem. When I finally determined that the switch was bad, it was still covered by warranty by Linksys/Cisco, so I opened an RMA ticket and returned it. Unfortunately, Linksys/Cisco "upgraded" my replacement switch to a SRW2008P, which has Power over Ethernet features I never planned on using. That by itself wasn't so bad, but it's my guess that the inclusion of PoE functions in this model required a tiny, super-loud internal fan to keep everything cool. This wasn't something I wanted or asked for, but, now that I am stuck with it, I am investigating options for replacing that little internal fan with something far quieter. For example, if I attach a larger fan to the outside of the chassis, I think it could push enough air to replace the stock fan that is currently there. Any advice on carrying this out? I have no interest in melting my switch due to insufficient ventilation.

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Update

Quite a few Linksys customers are having the same problem with other models in the SRW managed switch family, so when I broadened my search to include the SRW2024P, I finally found some helpful advice on how to open the switch and replace the fan. After reading the forum posts and looking at some pictures of a disassembled SRW2024P, I used a nylon spudger and a few plastic gift cards to gently pry apart my SRW2008P's case. Wedged between a clip and a notch in the metal was a standard 40mm x 20mm 12V fan. It was hardly a surprise that the fan's data sheet listed a 20dB noise rating, which I presume gets worse after it's been running for a few years and the worn bearings are growling with resentment.

The good news is that significantly quieter fans are available in the same size for as little as USD$10. The IXP1314 iXtrema Pro from SilenX is a 40mm x 20mm 12V DC case fan that snaps nicely into the same notch where the old fan went, so there is no need to rework anything with a Dremel just to install a replacement fan. The noise level dropped quite a bit with the new fan, but I think I can make it even quieter by installing a "noise reduction" cable that uses a resistor to throttle the fan speed. I'm only considering this additional step because I never use power over ethernet or any other feature that would generate very much heat on the switch.

Answer 1

As you suspected, small fans and high RPM make for a high noise level. These fans aren't good at anything except making enough pressure to get air past obstructions. In choosing your cooling mod tactic, take a good look at the system and see if the tiny fan is blowing air on one particular component, or just drawing air out of the case in general.

Replacing the fan with a large, slow one is definitely an option, providing you don't mind voiding the warranty for the modifications required. In doing the change, keep in mind that slower fans don't build as much pressure, so you have to provide larger, more free flowing passageways. That means you'll probably need to remove some metal, make a large hole or many small ones, to increase the airflow. If you're blowing in, you'll need to carefully seal the edges of the fan against the case. Silicon hobby glue or gasket maker is good for this.

If you're drawing air out, you should use the natural convection tendencies of the system by putting the fan out top, blowing upward.

In the days of 80mm case fans, I modded every system case I bought to a.) provide as many fans in as out, and b.) replace as many 80mm fans with 120mm fans as possible, and c.) use lower RPM fans, and more of them. The result was always cooler and quieter then the original setup, even if the original had only two fans.

Answer 2

For the time and effort you're going to spend pulling it apart and trying to find replacement fans that will a) fit and b) last, you may as well go and buy a Linksys SLM2008 switch instead - if you don't need all of the managed functions (eg. you get VLAN support, but not SNMP for instance) the SLM will do you fine, and it's smaller (and cheaper) than the SRW.

then you can redeploy the SRW2008 somewhere where the noise isn't a problem :)

Answer 3

I ran some 3com gear for many years after disconnecting the internal fan, however it did eventually die with the power caps popping after years of high heat (not actually over the limit, but steady).

If you have a pile of old heatsinks you could attach them to the hottest chips and that should be enough, especially as IIRC the power supply is external on those small linksys units.

Answer 4

Hello I also own this switch at there were to problems that I have resolved. I got this switch to handle the high bandwidth of security cameras and the POE to power them. This server also stores and feeds data to several locally connected machines. The managment feature allows me to control bandwidth and priorities.

PROs: This switch handled everything that I wanted it to do.

CONs: *This switch came with a very noisy fan. This fan ran at full throttle right after it's plugged in. Not temperature sensitive. FIX - I opened the switch found the power to the fan (12vots) and put an 8volt regulator (I'm considering going to 6volt).

*It also has a static default IP address of 192.168.1.254 which gives accessibility problems if you're not on the same subnet. My network is on 192.168.0.XXX (0 instead of 1). FIX - I logged into my DHCP router, changed the allocating IP addresses to start at 192.168.1.1 and end at 192.168.1.254. This gave my computer a new IP address on the same subnet then I was able to access the switch. Then I changed the Static IP address for the switch and went back to my router and returned the DHCP IP allocations back to 192.168.0.XXX.

It's been running great for about 3 months now. This switch is also located in a well ventilated area.

Those were the two major cons that I was able to resolve but for the price and features you can't beat it.

Answer 5

I have the SRW2008MP version, and the internal fan bearings were going bad. Mine is in a small data cabinet in the wall that abuts a master bedroom, and the noise was getting disturbing. My approach was different..... mount a nice Noctua 92x92x25mm 3-wire case fan to the top of the switch, externally. You can unscrew the front interface port and push that internally, and thru that hole see where the far right top plastic tab is to start your process of removing the front face. Getting the back face off was harder. Maybe the top metal part can be pressed forward off of the bottom metal part, but I did not think of that and worked hard enough to finally tear off one of the plastic hole back edges (one each right and left end) so that the back could then be removed. Then, unslid the top from the bottom. Not major damage. The power port is not attached physically to the back face.

The small Sunon fan is KDE1204PKV1, and you can look up the performance curves for that V1 version to see the max cubic feet/minute, etc. It is a 0.8W max fan, and clips into a metal holder at the far left side. Pull that out and disconnect its standard 3-wire fan plug from the circuit board. The Noctua fan will plug right onto that header, perfectly. When I looked up the Noctua fan with a Noctua low noise adapter in-line the specs showed greater air flow (by far), and that runs now almost silent, with huge improvement in quality and MTBF. You can find a cubic meter/hour to cubic feet/hour convertor via google, and divide by 60 to get cubic feet/minute to prove this to yourself.

The mechanics: I had a hole saw for 80mm fan size, and just used that, so there is about 3/8" internal metal overhang, but that is fine and good for strength. The center to center for the 92mm fan holes is 83mm. I centered my hole saw equally front/back over the top left side of the metal case (very near where the original fan was), and the metal is an aluminum alloy so it did cut (carefully) with the hole saw. I sawed from both sides to get the cleanest edges, and filed down the sharp edges some.

I had drill press drilled my 4 fan mount holes first, plus a center 1/4" guide hole for the hole saw's 1/4" center guide drill. I also drilled a 3/8" hole in the top left back black plastic plate, centered 1" in and 1/2" down from that top left corner..... that allows the Noctua LNA's smaller end to be fed thru and hooked to the header. I used the Noctua rubber fan mounts, and wrapped the Noctua lead around the fan outside for neatness (can zip tie it to the fan's outer corner ribs after drilling 1/8" holes in them). All went back together nicely, but be very careful as you finally put the front plastic face back on to not hang up on any of the front metal port thin edges. You can remount that programming port before you put things back together.

All very neat, and running virtually silently, with much better airflow than the original. The fan is pushing air inwards (as is the pattern with virtaully all computer fans it pushes towards the center fan hub label) down onto the left end of the internal PCB. There is a smaller number of case holes on the left metal case side, and more on the right metal case side so the air flow exits both sides, right greater than left.

This was a very worthwhile project.