From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nebojsa Trpkovic Subject: Re: Centrino: undervolting and further reducing heat Date: Wed, 18 May 2005 14:45:38 +0200 Message-ID: <428B38F2.5080907@gmail.com> References: Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: cpufreq-bounces@lists.linux.org.uk Errors-To: cpufreq-bounces+glkc-cpufreq=m.gmane.org@lists.linux.org.uk content-type: text/plain To: cpufreq@lists.linux.org.uk I use undervolted AMD64 on two gentoo boxes for months: 1. socket 754 nforce3-250gb, athlon64 3000+ (Newcastle core) overclocked to 2.4GHz and undervolted to run @1.45V 2. socket 939 nforce4 ultra, athlon64 3000+ (Winchester core) undervolted to run @1V at 1GHz and @1.275V at 1.8GHz (stable voltages suficient to run prime95 for hours were 0.9V at 1GHz and 1.175V at 1.8GHz but I like to be 110% safe so I've left extra 0.1V just in case) Ofcorse, I had to manualy modify powernow-k8.c ;) Daniel Bonniot wrote: > > Hi, > > I have a dothan 1.6 GHz processor, and i've been investigating how to > reduce heat to minimize fan usage. One very promising avenue is > undervolting. According to several online articles, there is a large > potential for undervolting. I ended up modifying speedstep-centrino.c > to test it out. Results are very positive: it can run under heavy load > at 1.6Ghz with only 972mV (down from 1340mV). This decreased > temperature by 10���C! At 600MHz, the minimum 700mV was sufficient. > > I understand that the driver needs to be conservative by default, but > given the huge benefits, it would make a lot of sense to offer a way > to specify lower voltages to those who want to. Has anybody > investigated this possibility, or already started working on it? What > would be a good interface to specify the voltages? > > > Independently of this feature, I wonder how it's possible to further > reduce consumption when the system is mostly ideal, and even 600MHz is > more than needed. The idea being to let the system cool down even more > in that case. Is there any existing way to achive this on linux? One > possibility I found in the intel docs is the IA32_THERM_CONTROL MSR, > which can reduce clock speed by 12.5% to 87.5%. Am I right in thinking > that it could be combined with speedstep to achieve even lower power > consumption states? Are there other possibilities? > > Cheers, > > Daniel > > > _______________________________________________ > Cpufreq mailing list > Cpufreq@lists.linux.org.uk > http://lists.linux.org.uk/mailman/listinfo/cpufreq >