On Friday 26 April 2002 09:52, Lars Fricke wrote: > Hello! > > I was just curious, how much electrical energy my system here needs to run > a LL-Test. Even if you don't let the system run if it is not used > otherwise, it seems to be quite a lot. > > On my P-III 933 (WIN XP), Prime95 needs about 15W power (measured with an > energy-monitor). That adds up to about 9 kWh for an exponent in the 13M > range for this system here.
If you have your system set up drop into standby mode when idle, there will definitely be a measurable increase in power consumption when Prime95 is active. Otherwise the increase in power consumption could be due to the FPU being active. Based on my experience with CPU core temperature monitors on PIII systems, I rather doubt that a PIII-933 FPU consumes as much as 15W above the normal load. I would think 15W extra for an Athlon FPU or P4 SSE2 would be reasonable. > > That does not even include the raised power-reqs for the power-supply fan > due to increased thermal load because i did not run the test a long time... Hmm. PSU fans normally run continuously. In any case the consumption would be low - computer case/PSU/CPU fans rarely consume more than 0.2A @ 12V (2.4W), often significantly less than this. > > Perhaps it would be interesting to find the system thats optimal for > LL-tests energywise ;) In terms of P90 CPU hours per kWh, we've got to be looking at P4 Northwood based systems - equipped with minimum peripherals. The main power saving that most people can make is to use an LCD monitor instead of a CRT. A 15" LCD monitor will use 150W-200W less power than a 17" CRT which has a similar visible screen size. There's a worthwhile saving in desk space as well. To get a real feel for this "value for money" question, surely you have to factor in the system depreciation cost i.e. the difference between the purchase and residual values plus the total cost of the power consumed over the working lifespan of the system. Since new systems depreciate very fast, whereas systems more than a couple of years old have virtually no resale value, keeping an old system running is often going to prove to be cheaper per work unit than buying a new system which might process work several times faster for roughly the same energy cost. In terms of sheer energy efficiency, there _may_ be an argument for P4M based notebook systems, but I think the "total cost of ownership" may be very high - not withstanding the difficulties that high-powered notebook systems often have in keeping cool when used for processor-intensive tasks. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
