alt Hacker NewsIf your computer is still doing bursty jobs during that period, it will use less power but still as much energy. Sure, you can reduce the power but if you aren't also reducing what you ask it to do, it'll just use that max amount of allowed power for a longer period of time.
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Technology Connections just did a timely video on the very topic of power vs energy.
As with everything, it depends. If you are going to do the same jobs regardless of the amount of time it takes, then yeah, dropping the max power probably just spreads the energy use over time. That doesn't usually help you save money, unless you have a very interesting residential plan.
OTOH, if it's something like realtime game rendering without a frame limiter, throttling would reduce the frame rate, reducing the total amount of work done, and most likely the total energy expended.
It is well known in the PC hardware enthusiast community that the last few digits of percent of performance come at enormous increases in power consumption as voltages are raised to prevent errors as clock speeds go up.
Manufacturers chase benchmark results by youtubers and magazines. Even a few percent difference in framerate means the difference between everyone telling each other to buy a particular motherboard, processor, or graphics card over another.
Amusingly, you often get better performance by undervolting and lowering the processor's power limits. This keeps temperatures low and thus you don't end up with the PC equivalent of the "toyota supra horsepower chart" meme.
1400W for a desktop PC is...crazy. That's a threadripper processor plus a bleeding edge top of the line GPU, assuming that's not just them reading off the max power draw on the nameplate of the PSU.
If their PC is actually using that much power, they could save far more money, CO2, etc by undervolting both the CPU and GPU.
All the modern CPUs will boost into high clockspeeds and voltage to get work done quicker but at considerably higher power draws per operation. On that side of the equation its clear that it uses more energy. The problem is the entire CPU package is on longer if you don't do that and this costs power too and so its a trade off between the two. Generally we consider there isn't much difference between them but I don't know about that having seen the insanity that was the 13th and 14th gen Intel's consuming 250W when 120W gets about 95% the performance I think its very likely moving down to power save and avoiding that level of boosting definitely saves small amounts of power.