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Forum Discussion
12v fan on 5v supply?
Just received my pair of Noctua NF-A4x20 FLX fans I intended on replacing the stock ones to reduce the noise of the refurbished switch I've just bought, which I waited until I received it to check the fan size and voltage before ordering these.
Just connected the Noctua in them, fired it up to check which way the fan blew, and it didn't turn at all, plugged the original back in and that works fine. Maybe the pin config is different, so I checked the volatge polarity only to find 5V's on the pins? How can this be?12v fan
26 Replies
- Hey did you ever get anywhere with this? I have the same switch and did the same thing - opened it up, saw the 12v fans and ordered the 12v noctuas which spin up for a second or 2 then stop.
Checked the voltage and it's putting out around 6v.
Opened up a GSM7248 and it had one of the exact same stock fans but that switch was putting out 12v from the pins. If I try that one in the M4100 it runs no problem.
If I try the noctuas in the GSM7248 they run and stay running and no fan fault light.
Should I just try the 5v versions of the noctuas instead?Hi,
wouldn't recommend the 5v Noctua either. I think where your getting the 6v is that the switch is just sending a lower voltage to have the fans run at a minimumal speed.
I even went to the expense of getting another set of 12v fans, think they were noiseblockers, and they didn't work! I got so frustrated, not only having to disconnect, take the switch out of the rack, take apart, that I sensed the wiring colours differentiate from all the others from the stock fan that Netgear phase reverse somewhere, anyway, cut a long story short after many variations I think I blew the 12v power rail.
so bought another switch off eBay, probably easier and cheaper than sending this for repair. Noticed an American eBay seller selling fans for the Netgear switch. He wasn't very forthcoming as to what voltages were where and what fans he's using and his prices are expensive and cost of shipping and import fees, I headed over to Aliexpress and have bought a selection of 3 or 4 fans that maybe suitable and should cost the same if not less than our US eBay guy. When they come in from China, I'll let you know, may have spare fans available!
- Let me know how you get on. The noctuas spun up in the GSM7248 when the positive and negative were reversed. I've ordered some 5v noctuas to try the same thing with reversing the pins.
Have seen the US seller on ebay as well but the cost plus shipping seems extortionate and no mention of what the noise output may be with those fans fitted.
I have so much Netgear kit I'd prefer not to have swap out equipment for other manufacturers and spend even more money, but the way they use fans in each device seems pretty strange.
I've made the same mods with other dell, hp and cisco switches and not had any problems like this.
Would be very interested to hear what results you get with the new fans.
I found this on the Noctua web site.
https://noctua.at/en/what-pin-configuration-do-noctua-products-use
It's been a while since I tried them, but they didn't work with various configurations. Unless you've tried otherwise? Thanks.
Ya know, ya'all could have solved this by just leaving the case of the switch open and buying a plain old 120v desk fan with a large diameter blade, and setting it to turn slowly and point at the switch circuit board.
it sounds to me like none of you either read or understood the earlier post that made the connection between airflow, rpm and noise.
Hi all.
I know this is an old thread but just a few comments:
1) Yes, for some daft reason Netgear don't use the normal pin configuration on their fan headers, thus necessitating dropping pins out of the fan's line socket and rearranging them, its not difficult to do but is annoying, get it wrong and you may not only damage the fan but the switch too. Most fan manufacturers use red for +ve, black for -ve and yellow for speed sensing.
2) The voltage at the header varies for fan speed control, using the wrong fan may mean that the voltage supplied for low speed may fail to turn the fan at all and hence trigger a fan failure alarm.
3) The comment regarding a supplier offering expensive fan options - if it is the supplier offering Sunon Maglev fans, then these are enterprise grade fans intended for many years of running 24 hours per day, I had some Compaq & HP servers using similar fans and they were still working perfectly after more than a decade of service. They may be overkill for amateur use but there is no doubt that they represent quality. In my experience cheap unbranded ones or those with poor quality badges suggesting they are rebadged unbranded ones that just about manage to work through their warranty period aren't worth the hassle. Certainly many on that well known auction site seem to rely on the fact that even if a product fails under warranty you won't bother with the hassle of returning it (if the seller still exists that is).
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