On Thu, Mar 22, 2012 at 10:51 AM, Alexander Leidinger < [email protected]> wrote:
> Quoting Luigi Rizzo <[email protected]> (from Wed, 21 Mar 2012 18:37:28 > +0100): > > I guess that the credit for power saving goes mostly to the CPU >> architects. Powerd only gives second-order savings, and C1 vs. C3 >> is ineffective, at least for HZ=1000 >> >> CPU Power (watts) >> freq idle 16 threads >> ----------------------- >> 200 48 51 >> 2200 52 83 >> 3200 54 115 >> 3401 56 118 >> >> powerd 48 118 >> > > I hope you all don't use a cheap PSU, but a _good_ high efficient one, > which really draws less power when idle instead of generating heat. Some > PSUs are only efficient in a sweet spot, instead of being efficient over a > broad range, even when being idle. See http://en.wikipedia.org/wiki/** > 80_PLUS <http://en.wikipedia.org/wiki/80_PLUS> for a quick and not so > in-deep overview (and the reality may differ from manufacturer to > manufacturer). > it isn't such a big deal in my opinion. The %efficiency at low levels is misleading if you don't factor out the 5-10W plateau for keeping the PSU alive (fan, ballast, etc.). See for instance http://www.techpowerup.com/reviews/Antec/HCG-520/5.html the table at the end of the page reports 6.73W of idle power. At 40W this PSU consumes 52.9W, so the apparent efficiency is 75%, but factoring out the idle power you go way up. cheers luigi -- > That does not compute. > > http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7 > http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137 > > -- -----------------------------------------+------------------------------- Prof. Luigi RIZZO, [email protected] . Dip. di Ing. dell'Informazione http://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL +39-050-2211611 . via Diotisalvi 2 Mobile +39-338-6809875 . 56122 PISA (Italy) -----------------------------------------+------------------------------- _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "[email protected]"
