If I buy 1200w PSU will it always draw and use 1200 watts from the wall?

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Kilgore23

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Hi guys, a quick question. If I bought this 1200 watt 80 plus plat psu would it only draw from the wall how much my computer is only using or will it always be using 1200 watts from the wall?

http://www.newegg.com/Product/Product.aspx?Item=N82E16817151140


And if it's not always using 1200 watts and only using what my system requires, then would I save any extra money on electricity at all if I choose to use a 1000 watt psu of the same brand and 80 plus plat certification?
 
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Dark Lord of Tech

Dark Lord of Tech

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JackNaylorPE

JackNaylorPE

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PSUs are most efficient at 50% load....so a 1200 watt PSU is most efficient at 600 watts.

So yes, the 1200 watter will be very efficient when loaded at 600 watts but it will be grossly inefficient at idle.

To give you an idea a highly overclocked Haswell w/ twin overclocked 780s will draw up to 730 watts from the wall....that's about 650 watts of output power.

Now if ya buying a large PSU to save money, it's never gonna happen unless you live in an area with extremely high electric rates.

Example:

Seasonic X-1250 Gold $230
Seasonic X-850 Gold $155

On 625 watt load .....

X-1250 = (625 watts / 90%) x 36 hours / week x $0.10 per kwhr / 1000 watts per kw = $2.50 a week
X-850 = (625 watts / 88.5%) x 36 hours / week x $0.10 per kwhr / 1000 watts per kw = $2.54 a week

To make up for the $75 ya spent on the bigger PSU, would take 1,875 weeks or 36 years for you to break even.

looking at it from a bronze to Platinum standpoint.

Platinum 850 = (625 watts / 90.5%) x 36 hours / week x $0.10 per kwhr / 1000 watts per kw = $2.49 a week
Bronze 850 = (625 watts / 83.5%) x 36 hours / week x $0.10 per kwhr / 1000 watts per kw = $2.69 a week

Seasonic Platinum is $190
Seasonic Bronze is $110

Thatz $80

At 20 cents a week .... will take 7.7 years to get ya money back and those are some pretty heavy usages. Precludes peeps with jobs, wives, kids, GFs etc :) Yes, my PC is on many more hours that that but that's pretty much the max load most see.... right now while tying this the system pulling 118.7 watts from the wall (Kil-o-Meter reading) ... with 20% of that the water pump.

So electricity cost savings while a pleasant byproduct is not going to prove out as a reason to get a high "precious metal" rating PSU. What ya should focus on is that to get that rating requires high quality components which will have better voltage regulation, produce less noise, have greater durability, produce less heat .... and due to all of the above, can actually help you get higher oCs.
 
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Kilgore23

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Thank you very much for your helpful information JackNaylorPE. By any chance can you tell me what it would be like running 23 hours a day? Maybe 22 for safe measure

I live in nyc, the kwh I think its 12 cent, actually I think it's gone up since april, I think it maybe 20 cents
 
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JackNaylorPE

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The Kilgore I know lives in Amityville

Running what ? Idle ?

Folding ?

Let's adjust for your 22 hours a day .... that's 154 a week: Multiply 20 cents bu 154 / 36 = 86 cents a week

Let's adjust for 12 cents .... Multiply 86 cents a week x 12 cents / 10 cents = $1.02 a week.

Let's adjust for wattage .... say typical system with a R280 - 365 watts as per
http://www.guru3d.com/articles_pages/geforce_gtx_280_review_test,11.html

Multiply $1.02 per week x 365 / 625 = 60 cents a week

Will take 3 years to get money back








 
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Kilgore23

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Sorry for being vague, what about running 23 hours always at about 90% utilization dual xeon 2650 (95w each?) server mobo with 2 sets of 4 banks occupied ram at 90% and say dual 770 gtx at full load. Sorry for bugging you lol
 
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