20190909, 01:47  #12  
"Curtis"
Feb 2005
Riverside, CA
2·2,311 Posts 
Quote:


20190909, 13:01  #13  
"Sam Laur"
Dec 2018
Turku, Finland
2×3×5×11 Posts 
Quote:


20190909, 13:34  #14  
Undefined
"The unspeakable one"
Jun 2006
My evil lair
2^{2}×19×79 Posts 
Quote:
Buy one of those power plug watt meters and use that figure as the basis for efficiency computations. 

20190910, 01:54  #15 
"Sam"
Jun 2019
California, USA
30_{10} Posts 
OK. I picked up several used WattsUp Pro meters a couple of years ago, and can put them to good use measuring AC power of my systems running Prime95.
Since virtually all of my systems running Prime95 are headless, with no display, keyboard or mouse attached, that is the way I'll be measuring the system power with watt meters. Questions. Will system power vary by the assigned exponents? Should I just take AC power readings while the systems are running their current assignments? Would it matter if the current assignment is LLD or PRP? Or should I pause the assignments and launch a specific torture test? Most of my systems are presently running PRP on exponents in the 88 million range. 
20190910, 03:19  #16 
"Curtis"
Feb 2005
Riverside, CA
4622_{10} Posts 
Try your various ideas, report whether outletwattage varies among any of those things. I doubt it, but I am prepared to be surprised.

20190910, 03:43  #17 
Apr 2019
5·41 Posts 
As I understand it, the smallest of the FFTs are allegedly the most tortuous, so I would expect them to draw a few more watts than larger ones.

20190910, 19:41  #18 
∂^{2}ω=0
Sep 2002
República de California
5·7·331 Posts 
Not necessarily  those small FFTs fit almost entirely in L1/2 caches, so tend to stress the CPU the most. Larger FFTs will spill into L3 and then into main memory, so may leave the CPU slightly less stressed but the overall system more stressed. Wattsatwall will tell the tale.

20190922, 01:36  #19 
"Sam"
Jun 2019
California, USA
2×3×5 Posts 
Here are two of my systems running Prime95 with AC power consumption measured using WattsUp Pro meters:
System #1  Intel NUC8i7BEH  Intel Core i78559U CPU (28W TDP)  16GB DDR42133 memory (2 x Samsung 8GB 2133 2Rx8 SODIMM, CL15, CR=1T)  Samsung 850 PRO 256GB SATA SSD  Akasa Turing fanless chassis 4 cores 1 worker PRP exponent 86831357, FFT=4608K ms/iter: 5.736 AC power: 47.2W System #2  ASRock Z390MITX/ac motherboard  Intel Core i99900T CPU (35W TDP)  Nofan CR95C passive heatsink (black pearl)  32GB DDR43600 memory (2 x Corsair 16GB 3600 2Rx8 UDIMM, CL17, CR=2T)  Samsung SM961 512GB NVMe PCIe SSD  Seasonic Prime Titanium 600W fanless power supply  ThermalTake Core P1 chassis 8 cores 1 worker PRP exponent 86846297, FFT=4608K ms/iter: 4.513 AC power: 59.6W Both systems are running headless: no display, keyboard or mouse attached. The second system draws more power from the wall than the first system, but cranks faster. Efficiency wise (iters/watt) they are quite similar. Last fiddled with by scan80269 on 20190922 at 01:40 
20190924, 05:34  #20 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
13·349 Posts 
Power bill becoming a concern
I'm thinking of replacing some outdated CPUs for MUCH MUCH faster but hopefully NOT a lot more power consumption.
What would I need to buy to produce the same LL or P1 throughput as these 4 CPUs: i52500 i53570 i53570 i53570K For example my i77820X produces about the same P1 throughput as the first 3 combined … at I suspect about 1.5 times the power draw of 1 of them. The first PC above also has a GTX980 GPU which I'd like to replace with maybe a 2080. OR....might I be better off by rather than getting a big honking CPU to get a GPU that is efficient at P1/LL? I understand Titan for example is really good at LL but not so great at TF whereas the 2080 is great at TF but so so at LL. Is there a card that is good at both? (That doesn't cost the same as a car?) 
20190924, 06:51  #21  
"Sam"
Jun 2019
California, USA
2×3×5 Posts 
Quote:
I've been a fan of low power Intel desktop processors, and am especially partial to the 35W series, such as i77700T (4core, Kaby Lake), i78700T (6core, Coffee Lake) and even i99900T (8core, Coffee Lake refresh). These are paired with dualchannel DDR4 memory at 2400 or 2666, which has nearly twice the clock frequency of DDR3 memory at 1333 or 1600, or more than twice if you count memory overclocking. I've recently found DDR43600 dualranked (16GB sticks) memory quite optimal for running Prime95 PRP with leading edge exponents (FFT=4608K or higher). My fastest system for Prime95 has a i75960X CPU (Haswell E, 140W) with quad channel DDR42133 CL14 memory, but its energy efficiency is substantially inferior to my i78559U and i99900T systems. So it comes down to whether you want to pursue high energy efficiency or high absolute performance. Favoring the former can help lower your electric bill and still achieve some increase in prime computing throughput. The latter may get you to speed record territory but with a sizable penalty in electricity cost. Last fiddled with by scan80269 on 20190924 at 06:52 

20190924, 11:08  #22  
"Mihai Preda"
Apr 2015
2466_{8} Posts 
Quote:


Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
How much do you pay for your electric energy?  em99010pepe  Lounge  31  20110214 01:57 
kinetic energy  science_man_88  Miscellaneous Math  8  20100529 04:14 
Energy Minimization  ShiningArcanine  Math  2  20080416 13:47 
VIA C3 efficiency  ET_  Hardware  4  20070327 21:29 
Energy efficiency for LL  markhl  Hardware  5  20040204 13:33 