Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!nntp.club.cc.cmu.edu!micro-heart-of-gold.mit.edu!bloom-beacon.mit.edu!panix!not-for-mail From: Grant Edwards Newsgroups: comp.os.linux.advocacy,comp.os.linux.embedded,uk.comp.os.linux Subject: Re: Google set to make its own energy efficient ARM Server chip Date: Mon, 16 Dec 2013 02:08:15 +0000 (UTC) Organization: PANIX Public Access Internet and UNIX, NYC Lines: 27 Message-ID: References: <03sru.770233$i75.479117@fx03.iad> NNTP-Posting-Host: dsl.comtrol.com X-Trace: reader1.panix.com 1387159695 10472 64.122.56.22 (16 Dec 2013 02:08:15 GMT) X-Complaints-To: abuse@panix.com NNTP-Posting-Date: Mon, 16 Dec 2013 02:08:15 +0000 (UTC) User-Agent: slrn/1.0.1 (Linux) Xref: csiph.com comp.os.linux.advocacy:210983 comp.os.linux.embedded:567 On 2013-12-16, unruh wrote: > Actually I suspect it is far higher than that. The theoretical maximum > is completely reversible computing, which should in principle create no > heat at all. That tends to be very slow. Next is to argue that each > erasure costs kT of energy. > Again they are far far far less efficient than that. Even 1kT per bit > operation would imply only 10^-21J/bit operation. Assuming 64 bit words > and 10GHz operation, that would still only imply 10^(-9) watts of power > consumption. Instead what we get is something like 100W so, that is > 99.99999999% of the power going into heat rather than useful > computations. >> 100% of the power in a data center turns into heat. > > Actually no, some of it goes into reducing the entropy of the system. But surely that's only temporary. Does entropy continue to be reduced indefinitly for as long as a computer is being run? Or does it reach some sort of "average" level and from then on you're just transitioning between different configurations of similar entropy? -- Grant Edwards grant.b.edwards Yow! You can't hurt me!! at I have an ASSUMABLE gmail.com MORTGAGE!!