From: user5857@newsgrouper.org.invalid   
      
   Terje Mathisen  posted:   
      
   > George Neuner wrote:   
   > > On Wed, 24 Sep 2025 21:08:10 +0300, Michael S   
   > >  wrote:   
   > >   
   > >> On Mon, 22 Sep 2025 19:36:05 GMT   
   > >> MitchAlsup  wrote:   
   > >>   
   > >>> Big servers have rather equal power in the peripherals {DISKs, SSDs,   
   > >>> and NICs} and DRAM {plus power supplies and cooling} than in the   
   > >>> cores.   
   > >>   
   > >>   
   > >> Still, CPU power often matters.   
   > >   
   > > Yes ... and no.   
   > >   
   > > 80+% of the power used by datacenters is devoted to cooling the   
   > > computers - not to running them. At the same time, most of the heat   
   > > generated by typical systems is due to the RAM - not the CPU(s).   
   > >   
   > I am quite sure that number is simply bogus: The power factors we were   
   > quoted when building the largest new datacenter in Norway 10+ years ago,   
   > was more like 6-10% of total power for cooling afair.   
   >   
   > . a quick google...   
   >   
   > https://engineering.fb.com/2011/04/14/core-infra/designing-a-v   
   ry-efficient-data-center/   
   >   
   > This one claims a 1.07 Power Usage Effectiveness.   
      
   All of this depends on where the "cold sink" is !! and how cold it is.   
      
   Pumping 6ºC sea water through water to air heat exchangers is a lot   
   more power efficient than using FREON and dumping the heat into 37ºC   
   air.   
      
   I still suspect that rectifying and delivering clean (low noise) D/C   
   to the chassis' takes a lot more energy that taking the resulting heat   
   away.   
      
   Flash will have low         heat signature   
   DRAM  will have significant heat signature   
   DISKs will have significant heat signature   
   GPUs  will have significant heat signature   
   CPUs  will have significant heat signature   
   Motherboard has low-medium  heat signature   
      
   >   
   > Terje   
   >   
      
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