Wondering is anyone has experience with fan hardware inside 891? Has anyone replace the stock fan and if so, what did you replace it with?

Thanks.

Welcome to SPCR,

I'm not familiar with a Cisco 891 -- can you post a picture and / or the fan size?

Thanks for reply Neil. I wish I could provide the fan size and type. Unfortunately, I have not been able to find the information online. This is for a device I have not purchased yet because I am not sure I can replace the fan to reduce the fan noise. I was trying to figure this out before I drop money on it.

If anyone can provide the type of fan in the cisco 891, I would appreciate it. The datasheet is here: http://www.cisco.com/en/US/prod/collateral/routers/ps380/data_sheet_c78-519930.html

Are you sure there is a fan in it? It has vents only on the side(s):

http://www.btecanada.com/products/index.php/default/catalog/product/view/id/9112/s/cisco-891-integrated-services-router-cisco891-k9/category/13/

Neil, that is a great observation and question. I found a spec sheet awhile back where it lists the noise as 32 dba but problem is that I can no longer find that spec sheet. Been asking around the cisco forum and can't get a definite answer on it. Checked the spec sheet at cisco and it doesn't say either way: http://www.cisco.com/en/US/prod/collateral/routers/ps380/data_sheet_c78-519930.html

I'm stumped

Neil, I got a picture of the fan. Any recommendations on a silent upgrade?

Ooo-boy, that looks like a 40mm fan? Small fans like that are nearly impossible to replace with a similar fan and be any quieter, or be enough cooling. They are simply so small they have to spin like crazy to move any air at all.

The only thing I can think of is to put the Cisco unit in a larger case (rack?), or a duct of some sort, that has a large fan that pulls air through the Cisco. If the Cisco's fan doesn't have a thermal control, then it might have to be disconnected to keep it quiet.

Thanks for the help Neil. Happy Holidays.

I have the 891 installed on my desk, and it was an upgrade from the fanless 871 so I can definitely notice the fan noise.

It's mostly a vibration related noise. I tried placing the 891 on top of some noise reducing foam that I had left from a foam order from one of the vendors recommended here but that didn't seem to help much.

I wouldn't go back to the 871 just because of the noise though because the 891 supports PoE, and I have 2 IP Phones on my desk, too, so I've saved quite a bit of clutter with the elimination of 2 AC Adapters. The 891 is also a much higher performance router not to mention the addition of 4 more Ethernet ports so I don't have to do as much juggling between all my IP devices.

As an experiment, I tried covering up the vents on the side and that seemed to deaden the noise. I'm not recommending this as a solution since I don't want my VPN router to overheat but maybe it's a clue as to what we can do to silence the fan noise.

I was afraid the noise would be a problem. You recommend another L3 Ciso device that is fanless? I can't seem to find one that is comparable to the 891. I was looking at the 1811 but it has a fan also and is louder I believe. The spec sheet has it rated at 34 dB.

Thought I could change the fan but earlier post said that wouldn't be feasible because the fan is difficult to replace.

They are supposed to be coming out with a fanless version of the 881, so I am hoping that means they are working on a fanless version of the 891, too. Since the 891 came out recently, though, that probably means it's not going to be anytime soon (waiting another year).

Would sticking a FanMate2 on the 40mm fan work?

It appears to be a standard 3-pin plug on the fan, so yes a FanMate2 would slow it down. But, be aware that a tiny fan moves a tiny amount of air, and slowing it down means it moves even less.

If you put the unit inside a case with a big fan on it, you can move air through it quietly.

What's a FanMate2? How does it work and where can I get it?

A Zalman FanMate2 is an inexpensive analog fan speed control. You manually set the maximum speed, and if the power header is thermally controlled, then the fan speed will vary. But since the FanMate2 is a manual control, and if the power header is a fixed voltage, the speed will be a single speed.

So, I got another 891 to test with, and it, too, has the droning fan noise.

I made some crude sound measurements using the Voice Memo app on my iPhone 4 and stuck the iPhone about 1" away from the fans in question. As a comparison, I made a 2nd measurement of the 120mm fans on my open air tech bench where my desktop PC resides.

I opened up the 2nd 891 and found that the 40mm fan is mounted via a plastic bracket to the bottom of the 891 chassis, and then the top lid of the chassis lies on top of the bottom part of the chassis and secured by 3 screws in the rear of the unit.

The 40mm fan itself is quite noisy, and it didn't seem to make much difference when attached to the FanMate2. Cisco has stated that the fan will throttle up and down depending on the temperature of the router.

The physical width of the case is ~12.5".

-shroud-fan--> Wireless Daughterboard w/ passive heatsink --> CPU passive heatsink --> vents
[0--.75-1.5-----2.5-------------------------------------5-----7.5---------------9-----12.25/12.50-]

When everything is sealed, the airflow is pretty good as I can definitely feel air out the other side of the case where the vents are as it sucks cool air from the left side (looking at the router from the front).

I tried attaching the files to this post, but after posting, I can't find them anywhere.

So here's a link to a zip containing all the sound files I created:
http://hotfile.com/dl/99985178/dca6976/ ... e.zip.html

Maybe this is the next best alternative ... somehow figuring out a way to do push/pull using 120mm intake/exhaust fans in a larger pizzabox case.

Dunno which one might serve the purpose or how effective it would be.

I'd envision having to leave the top of the 891 off, putting the bottom chassis into the larger case, and having to fish all the cables through the PCI slots.

---

Or, what about experimenting with replacing the stock NMB (Model: 1608KL-04W-B59, 8500rpm, 9.45 CFM, 33 dBA) 40mm "double ball-bearing" with one of these:

Scythe

Model Name: MINI KAZE ULTRA 4cm Silent Fan
Model Number: SY124020L
Manufacturer: Scythe Co., Ltd. Japan
Dimensions: 40 x 40 x 20mm
Fan Speed: 3,500rpm(±10%)
Fan Noise: 19.56dBA
Airflow: 4.86CFM
Rated Voltage: 12V
Rated Current: 0.07A
Connector: 2-pin (3-pin adaptor included)
Bearing Type: Sleeve Bearing
MTBF: 30,000 hours

Model Name: Mini Kaze 4cm Silent Fan
Model Number: SY124010L
Dimensions: 40x40x10mm
Fan Speed: 3500rpm(±10%)
Fan Noise: 14.00dBA
Airflow: 4.11CFM
Rated Voltage: 12V
Rated Current: 0.06A
Bearing Type: Sleeve Bearing
MTBF: 30,000 hours

My Cisco 891 is very noisy. I pulled out the fan and found that it's noisy even outside of the case.
My 891 sits on my desk behind my monitors. Even with heavy video conferencing, phone PoE, wireless and wired traffic, the case doesn't even get warm. It feels like it's safe to lower the airflow.
I had a FanMate 2 on hand, so I tried that. All it does is change the frequency of the fan noise.
On Cisco's internal forums, some people suggest unplugging the fan. I don't think I want to do that, so I'm going to try KY's suggestion and order the
Scythe "MINI KAZE ULTRA" 40 x 20 mm Silent Mini Fan. It's only $5.58 on Amazon.

I'll post again if that fan works.

The Scythe "MINI KAZE ULTRA" fan did a good job of quieting the Cisco 891. It's better than before, but still not silent. As soon as you touch the fan to any point on the chassis you can hear it resonating. I think if you want the 891 to be completely silent you need to put it into a different box or use passive cooling.