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I have a mining rig (computer using its processing power to calculate hashes in order to eventually be rewarded with cryptocurrency tokens.)

The program I use to mine tells me each time the power consumption of my hardware (basically only the graphics card power consumption) which is around 900 watt stable (it measures it every few seconds.)

I also have a meter which shows me the total power consumption drawing from the mains/plug.

I noted the following discrepancies (or at least I found them to be.)

While my hardware is under the same load (99% +-1%) constantly and my mining program displays the same power consumption (900 watts) independently of the outside temperature while the meter on the plug when it is a warm day shows around 980 watts consumption but at night when it is cold (I keep my rig in a shed thinking that cold would do good in terms of stability and maintaing low component temperatures while under load) the meter on the plug shows more than 1080 watt usage.

Is there something in the circuitry of the meter that could mess with measurements because of low room temperature or do electronics (be it my computer's powersupply or my graphics cards) consumer more energy while operating on low room temperatures?

Note that the mining program power draw measurements are relatively accurate because either in cold or in warm weather if I increase the power consumption of the cards it shows an increased value while the meter on the plug also shows a somewhat proportionally increased value.

EDIT: By cold weather I mean about -5 to 5 degrees C and by warm anything above 12ish degrees.

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  • \$\begingroup\$ MOSFET resistance increases with temperature, as do typical resistances elsewhere in the computer. How "cold" is cold? Cold at night in the shed for me means anything below -15C. \$\endgroup\$
    – DKNguyen
    Feb 28, 2021 at 22:54
  • \$\begingroup\$ cold about -5 to 5, warm about 10-15, is there anything I could do to remedy that effect? my target is to keep power consumption low without sacrificing on system performance. \$\endgroup\$
    – papajo
    Feb 28, 2021 at 23:00
  • \$\begingroup\$ Your OS is going to be a factor here. Is it throttling your processor? Are the fans running full tilt? I don't think the characteristics of the transistors will matter much at all. \$\endgroup\$
    – Elliot Alderson
    Feb 28, 2021 at 23:33
  • \$\begingroup\$ CMOS transistors will switch faster when cold, but most of the power consumed is for charging the gates and other signal path capacitance. This doesn't change much over temperature. I suspect a secondary affect like Elliot eluded to. \$\endgroup\$
    – Mattman944
    Feb 28, 2021 at 23:54
  • \$\begingroup\$ @Mattman944 So it is not likely that my meter gets a little off when cold? (it's this one daraz.pk/products/uni-t-power-meter-ut230b-eu-i100952266.html) \$\endgroup\$
    – papajo
    Mar 1, 2021 at 0:03

1 Answer 1

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Many modern CPUs and GPUs automatically scale down their clock speed and/or number of operational cores if they are too hot in order to prevent dangerous overheating. This could well be the cause of your discrepancy; if it is (which you should be able to test by monitoring your number of hashes per second in different conditions) you may need to install additional cooling.

While it is perfectly possible for either your consumption to change a little without this happening or for your meter's calibration to drift as temperature changes, I would expect both to show the opposite effect,i.e. reading higher power consumption in warmer conditions, so I don't believe this is likely to be the case.

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  • \$\begingroup\$ I thought of this too. Thermal throttling could explain why power consumption would go UP when temp goes DOWN. But why does the power meter for the rig stay pegged at 900W? \$\endgroup\$
    – user57037
    Mar 1, 2021 at 7:30
  • \$\begingroup\$ no the clocks (both GPU and GPU vram , cpu isnt used anyway during mining ) are constant on the highest level I set them to be and my hashesh are constant as well. It is just that when the room is much colder the meter on the plug shows higher consumption (the program gives the same consumption) \$\endgroup\$
    – papajo
    Mar 1, 2021 at 17:57

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