SGI: Hardware

I managed to obtain a Netgear 48-port Gbit switch rather cheaply (GS748T), but it's surprisingly loud. Anyone
have some ideas about suitable replacement fans? They look like normal 4cm fans (rough measurement, I've
not opened the case), but by default are running at max speed. I'll never be using more than 3 or 4 ports
on the switch (for the moment) so the fast airflow is kinda overkill. Recommendations? Quieter fans I can use,
or a way of slowing down the existing fans? Or I suppose I could just disconnect 1 or 2 of them...

I want to link up some of my SGIs that have optical ports, but right now this thing's like having a miniature
hurricane in the room. It's not my main switch and will be off most of the time (main switch is a DLink
silent 8-port Gbit), but will be used whenever I'm accessing one of my SGIs that has optical Gbit.

Thanks!

Ian.

mapesdhs wrote: I managed to obtain a Netgear 48-port Gbit switch rather cheaply

You did well!

The Netgear switch behind me in my office is completely drowned out by PCs, Octanes, Macs... I wasn't aware that it made any noise at all. Surely the moment you power up an Octane the noise of the switch becomes inconsequential.

fieldframe writes:
> You did well!

Yup!


> ... Surely the moment you power up an Octane the noise of the switch becomes inconsequential.

Nope, it's much louder, perhaps because the fan noise pitch is a lot higher. Besides, my Octane2 is under
the desk at the back by the wall, so I don't really hear it that much.

Ian.

You can use a voltage-dropping resistor or diode in-line to slow the fans down. Also, don't overlook something like the Zalman Fan-Mate, which is basically a variable resistor connected to an emitter-follower transistor which allows you to adjust your voltage to whatever your speed requirements are, they're quite cheap and seem pretty useful. Or just replace the fans with something slower/quieter, there should be lots of options from the PC fan manufacturers. You should be able to find lots of recommendations on the 'silent-PC' sites as to options, even in the small sizes. Someone will have done a test somewhere...

Dr. Dave writes:
> You can use a voltage-dropping resistor or diode in-line to slow the fans down. Also, don't overlook something like the Zalman Fan-Mate, ...

Thanks for all that! Come to think of it, I think I have a couple of those Zalman widgets, came with some Zalman fans I bought.

Cheers!

Ian.

I've come across this problem so many times it isn't even funny.

Manufactures like to cram high-speed fans in network equipment, so they're covered when the device is operating at *full load* (ie, 48 active ports). Most switches I've seen will throw off a fair whack of heat when they're loaded, too. I've never seen a switch with thermal management on it either, these things are meant to be stuck in a closet anyways.

So.

I would not recommend that you fiddle with the fan to permanently /limit/ it's speed. You can damage your switch doing this.

I would highly recommend that you purchase one of these:

http://www.frozencpu.com/products/5299/ ... ?tl=g34c17
http://www.frozencpu.com/products/5298/ ... ?tl=g34c17

Both of these are designed to bolt onto the fan itself. One is a solder version (you'll need to put it in the middle of the fan power cable!), the other is a 3-pin version (most fans use this connector, the switch might too). They both throttle the fan speed depending on temperature and are relatively cheap. Therefore, your switch fan will run at the speed it needs to, depending on the load (and heat dissipated) from the switch.

I've installed these gadgets on countless switches, from 3Com's to Netgear and Linksys. Linksys I know usually uses the 3-pin connectors (so you don't need to solder anything), but I'm not sure about NG.

-DN

I had an 8-port gigabit switch with a noisy fan. I ended up opening the switch chassis, and used some thermal epoxy to attach a long heatsink across all 8 of the chips. Then drilled some holes in the case top for ventilation and removed the noisy little fan altogether. Now it's silent!

That was 3 years ago, it's been running 24/7 ever since.

Lupin_the_3rd wrote: I had an 8-port gigabit switch with a noisy fan. I ended up opening the switch chassis, and used some thermal epoxy to attach a long heatsink across all 8 of the chips. Then drilled some holes in the case top for ventilation and removed the noisy little fan altogether. Now it's silent!

That was 3 years ago, it's been running 24/7 ever since.

I did something similar with a 24 port 3com. I had ordered a Thermaltake CL-P0200 80mm from Newegg, and they sent me one case instead of one unit. 6 for the price of one.

I measured out 2 holes right above the psu (which the other fans had been adjacent to, except on the side) and dremel'd them out. I removed the fans from their heatsink, and mounted them on the 3com. According to the infrared thermometer that my mechanic buddy lets me borrow, the psu heatsink is about 4-6 degree's cooler while the rest of the box is about 6-8 degree's cooler under medium load. It has run flawlessly for about 2 1/2 years now.

Very quiet, very cool.

Dennis Nedry writes:
> http://www.frozencpu.com/products/5299/ ... ?tl=g34c17
> http://www.frozencpu.com/products/5298/ ... ?tl=g34c17

Thanks for the info & links! I'll see if I can find a UK source for those items. However, I'd still like to replace the fans with
low-noise versions anyway if I can.

Ian.

Dennis Nedry wrote: I would highly recommend that you purchase one of these:

couldn't you just get a replacement fan with a built in thermresistor?

A long time until I was finally able to look into this properly, but what an historic day to get working on it (I hope!)...

I wasn't able to find anything in the UK like the NoiseMagic ThemoControl NMT-3, so instead I've decided to replace the
noisy fans in the Netgear switch with these:

http://www.quietpc.com/gb-en-gbp/produc ... /mini-kaze

and also fit at least 2 of the fans with this (I have a feeling perhaps only one fan will be needed most of the time):

http://www.quietpc.com/gb-en-gbp/produc ... s/fanmate2

I reckon this should work very well. Just to compare btw, the fans fitted by default in the Netgear switch are model
EFB0412VHA, specs for which are: 12V, 8000rpm, 9.46cfm and a whopping 37.5 dBA.

Atm I'm waiting to hear if the seller can do a bulk price - might get a few more for dealing with future project needs.

Thanks for all the help!!

Ian.

Hi, was just wondering if this solved the problem for you? I've got the same issue and am thinking of doing the same as you.

Alas in the event I never had the time to sort it out. I have all the parts but haven't done the mod yet. However,
it should work fine. The replacement fans are much quieter.

I have to reorganise my desk and sort out a new set of shelves before I can setup the Gbit switch.

Ian.

I actually went ahead and did it myself last night. At first I thought I'd broke it because I couldn't hear a thing! It worked fine though. The only small snag was that only 2 of the three fans are 10mm in depth, the third is 20mm as it connects directly to the long heatsink at the front so I've had to order a deeper mini-kaze. Other than that it was easy as pie and it works fine and makes virtually no noise!

Excellent!!!

Re the deeper fan, I could probably leave out the 3rd fan completely, or just rig something up to fill the gap, since I'll only
be using at most 4 to 6 ports. I bought the switch because I needed one with the option ports to hold Gbit fibre modules,
in order to support optical Gbit Ethernet cards for O2. Thus, power consumption should be pretty low. Yeah I know, 48 ports
is overkill, but 16 port and 24 port models were more expensive; I bagged mine for a bargain price of 95 UKP.

Ian.