PSU question..

dtiao7eb

dtiao7eb

Member
kinda random question...

when a psu is say... 1200watts... is it constantly using all 1200 watts? or is it able to handle 1200watts.

i'm in the process of building a 24/7 server comp... i was gonna get a nice sized power supply... but not if its gonna destroy my power bill lolz probably only need about 500watts... but was gonna get 1000w just for kicks and ensure(insure?) that i get enough power to all of my hd and components :)

thanks
 
a 1000w PSU running 24/7 would cost about $110 extra a month on your bill.really depends on how much you pay per kWh.

edit: wattage x hours used ÷ 1000 x price per kWh = cost of electricity (the $110 is being that you pay .15 cents a kWh)
 
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dtiao7eb said:
kinda random question...

when a psu is say... 1200watts... is it constantly using all 1200 watts? or is it able to handle 1200watts.

i'm in the process of building a 24/7 server comp... i was gonna get a nice sized power supply... but not if its gonna destroy my power bill lolz probably only need about 500watts... but was gonna get 1000w just for kicks and ensure(insure?) that i get enough power to all of my hd and components :)

thanks
Click to expand...

A power supply only puts out as much watts as your system uses. If you have a 1200W power supply and your system only pulls 500W. Thats all its putting out.
 
tech savvy said:
a 1000w PSU running 24/7 would cost about $110 extra a month on your bill.really depends on how much you pay per kWh.

edit: wattage x hours used ÷ 1000 x price per kWh = cost of electricity (the $110 is being that you pay .15 cents a kWh)
Click to expand...

If you want to know (estimate) costs, then you're both forgetting about efficiency losses. What this means is, if you want to convert AC to DC and you require 300W, it will draw 348W from the wall (84% efficiency). This obviously increases the costs by 16%.

For example, lets assume maximum draw of 1200W for now...

1200W PSU running 24/7
Assuming 84% efficiency @ 112V @ 100% load

1200W = 1.2kW
Hours 8760 per year
Total annual consumption = 1.2 x 8760 = 10,512 kWh

Efficiency losses
Hours 8760 per year
Efficiency losses = 1.2 x 8760 x 0.16 = 1,681.92 kWh

Total consumption = 10,512 + 1,681.92 = 12,193.12 kWh annual

Electricity Costs ($/kWh) = $0.15

Total cost per annum = 12,193.12 x $0.15 = $1,830

Of course this is at maximum draw. Multiply this by a proportion of load to get your figure. If you say will draw 500W (unlikely), it will be 500/1200 x $1830 = cost. But as Strangle said, you draw from the wall the load + efficiency losses up until the rated power specification.

Total annual costs ($) (100W - 350W) assuming $0.15 / kWh and 84% efficiency across load spectrum...

100W load = $152.50
150W load = $228.75
200W load = $305
250W load = $381.25
300W load = $610
350W load = $533.75
 
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