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switching-PSUs: why can't you usually exceed the 50% of declared power?

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PKTKS:

--- Quote from: engrguy42 on May 24, 2020, 12:37:52 pm ---FWIW, it's a myth that higher efficiency power supplies save you a lot of money on your electric bills. Do the math.

In the US the average cost of electricity is about 13 cents per kWH. In Brazil it's like 14 cents (US). If you calculate the difference in kWH ACTUALLY used with a 90% efficiency power supply versus an 80% power supply it amounts to maybe a few US $$ per year. A bit like the cost savings by running around your house and turning off a 50 watt light bulb when it's not being used.

Unless you run your computer at maximum load 24 hours a day, 365 days a year....

--- End quote ---

Thanks...  for the clever comment.

ABSOLUTE TRUE.

This is a total wrong argument. The savings on the bill
promoted by such "ratings" 80% 90% gold plus shit are garbage.

Those PSUs are targeted to high end PCs where you use
hungry power GPUs which waste awesome 700W of true power
plus ownership costs.

SOHO and POS are well below 300W and the cost focus
is more on hardware wearing out soon than the mains bill

Their air conditioner is ORDERS OF MAGNITUDE above...
on the mains bill  and their pile of PCs are a real problem.

So saving more than double the cost on EACH OF THEM..
is a very good argument with their managers.

Paul

wraper:

--- Quote from: engrguy42 on May 24, 2020, 12:53:09 pm ---Power supply efficiency, for most, amounts to maybe a few $$ per year. If that matters, then fine. As long as people are aware, and not just handwaving on stuff they don't really understand.

--- End quote ---
If computer works 8 hours a day, when comparing decent and cheapo PSU, power consumption difference over about 1-3 years will cover price difference and in some places even buy you additional good quality PSU.

coppice:

--- Quote from: engrguy42 on May 24, 2020, 12:37:52 pm ---FWIW, it's a myth that higher efficiency power supplies save you a lot of money on your electric bills. Do the math.

--- End quote ---
For most people moving from an 80% efficient supply to a 90% efficient supply in their PC will not save much in electric bills, because their PC is only working hard for a small percentage of the time. However, for server, telecoms and other high power applications running flat out 24 hours a day every extra percent of efficiency brings a big enough reduction in power bills to justify significantly higher complexity in their power supplies. Try looking at the materials used to promote multi-kilowatt supplies in the 95% to 97% efficiency area. Its all about cost breakdowns over the life of the equipment.

For consumers a shift from 80% efficiency to 90% efficiency is not useless. Halving the supply's heat output helps compact machines to run cool with a very quiet fan.

engrguy42:

--- Quote from: wraper on May 24, 2020, 12:58:00 pm ---
--- Quote from: engrguy42 on May 24, 2020, 12:53:09 pm ---Power supply efficiency, for most, amounts to maybe a few $$ per year. If that matters, then fine. As long as people are aware, and not just handwaving on stuff they don't really understand.

--- End quote ---
If computer works 8 hours a day, when comparing decent and cheapo PSU, power consumption difference over about 1.5-3 years will buy you additional good quality PSU.

--- End quote ---

Again, you're free to believe whatever you want, but if you actually look at the numbers for your ACTUAL usage you may find out that's not the case.

Mechatrommer:
please also remember a PC is not the only thing in a (full family) house. TV, hifi, wifi router etc use SMPS. and sometime 3-5 PC/laptop in the house. promoting for extra 10% efficiency and making a habit to turn off appliances when not in use can buy you a good toy within a year.

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