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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 th...
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.
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.
Can't see anything strange - except of that people try to put in replacement fans able to create a light airflow (40% less than the 5000 min^-1 Delta fan variant, max rotation speed 5000 vs. 13000 making less than 25% of the max airflow, and some 85 of the max air pressure). How easy it is to build a "silent" fan at these limitations (lower fan tip speed - this is whee most aerodynamic noise is coming from). In my opinion a fan not fit for replacing in any of these switches, even if it rotates, and the Fan error LED does not go on.
If an amateur aircraft builder would ask me if this engine and propeller combination ("hey I found a sooo silent solution and my Piper L-4 with it's Conti A-65 flies great") would fit his next project designed for a much bigger engine and better prop, he will hear that the takeoff run over 50 ft obstacle will be much longer, the max rate of climb will be nuts, and last but not least the cruise speed will be poor. Overall, doing so would be a major safety risk, and I'm most likely unable to sign-off his project powerplant.
The FFB0412SHN nominal 12 V models have a rated operating voltage range from 4.5 to 13.8 V as per the specs - so 5 or 6 V voltage is OK. As DigitalVT mentioned, this lower "cold switch" fan voltage is certainly implemented this way to allow lower minimum rotation speed - and it will come up to higher voltage if required. Depending on the Noctua fan motor design, it's well possible that the fan does rotate easier in the non-intended rotation direction. For example small classic DC brush engines (think of what Mabuchi builds in zig millions of and millions of one model every year) are timed to rotate in one direction for ideal power output including the torque. To let them rotate backwards, a much lower voltage is sufficient, but power out and efficiency will be ways below. And yes, several Mabuchi can be ordered from the factory for alternate rotation direction, and many can be re-timed by bringing the brushes for it. Enough said on this excursion here.
Note: There is absolutely nothing wrong with the Noctua fan design and specifically the NF-A4x20 (FLX just designates the add-on electronics for interfering even more) - if is deployed where the massive lower cooling capacity of the airflow is acceptable - they just can't replace any FFB0412 variant.
Am sure the stock Netgear fan is great for switches in an enterprise scenario where the switch is under full load, speaking for myself, just want a switch with enough ports that can accomodate various connectivity around the home without additional switches elsewhere or having to manually repatch, thus the device itself wouldnt be under much load, therefore a slight breeze from these quieter fans may be enough to keep the Netgears internals cool enough to be accpetably quiet in a home environment?
I've got 8x PoE cameras, 3x PoE AP's, a PoE Cloudkey and multiple wired ethernet devices. My thoughts that a Noctua or other "quiet fan" running at 100% capacity keeping the internals cool when the switch is not busy and then may take longer to cool for the "short" busy times, is an acceptable useage, giving a quieter environment?
Hello pn23,
sadly still waiting for delivery. It's been two months tomorrow since I ordered it, the tracking mentions it arrived in destination country on 15th Feb and on the 22nd Feb it was accepted by the last mile courier. Have received two items I've ordered weeks after, and many other items have also followed in the black hole/depot these fans are sitting in.
Maybe this week? But have been hoping that for a number of weeks!
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