Bernd Felsche wrote: > Ian Cowley <[email protected]> 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 _______________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
