[asterisk-users] Quiet 24 port POE gig switch

[Steve Underwood]

Bernd Felsche wrote:
> Ian Cowley <ianc at moffat.co.uk> wrote:
>
>   
>> Beware PoE switches that can't handle Class 3 (15W) on all ports.
>> Most have fans because 24 (or 48) x 15W is hot!
>>     
>
> That's the power supplied .. which'd be at the far end of the wire.
>
> The efficiency of the PSU plays a big part in the heat dissipation.
> The push to compact dimensions doesn't help ... a 400W or
> thereabouts PSU with 24 independent outputs in 1U height? I suppose
> if the switch were quite deep it could be workable and quiet.
>
> The problem isn't simply of being "fanless". But being quiet.
> Preferably below 32 dBA at 1 metres for most offices.
>
> You can do that by using fans other than the tiny, whiney, 40mm fans
> that vibrate at 6000 to 18,000 Hz. A couple of 80 or 120 mm muffin
> fans at the back or front, pushing air in (hence the deep
> dimensions), but the top and bottom would need recesses to allow
> sufficient airflow when the positions above and below are filled.
>   
So, size does matter after all. :-)

24 x 15W => 360W. Its not that big a supply really, and spread across a 
1U case its not that dense a supply. A 360W desktop PC supply can be 
pretty quiet, so its sad none of the 1U chassis supplies are. Probably 
if they used a large impeller fan they could get the noise down. I guess 
they assume these things will be in cupboards or data centres where 
nobody cares. This is a poor assumption.

Regards,
Steve