How to reduce the cost of electricity of PSU

[bratsos]

Many guys buying new computers desktop with huge PSU supporting...

When a computer is new model, worst the cost of eating electricity...

But one old computer with PSU eg: 500Watt, is good to be running or costly???
If old computer Core Duo 2.Ghz desktop with a nVidia GPU 8800 and dvd -rw unit... To day cost about 100$ or less..

But 8 hours every day operate will add about 50$ more payment in to electric account every month...

My computer is Celeron 3.2Ghz with GPU GF-7950GTX2 and sound audigy...
And running about 10-12 hours every day.
I have combine with that a PSU 185Watt.

But to success, i have remove the dvd-rw unit.
And running OK :good: (The only issue is some games such HL-2 or World of Tanks running a bit slower, but no big matter, if i wanna save 50$ every month)

When you are using a old computer for linux (linux bring the old computers to life...) make sure PSU no drain much power or pay the price in electric account...

 

[johnb35]

You are way overreacting. Running a high end power supply will not cause your electric bill to go sky high. You will only use as much as power as your system needs.

 

[linkin]

You are way overreacting. Running a high end power supply will not cause your electric bill to go sky high. You will only use as much as power as your system needs.

Pretty much. Efficiency plays a role as well but unless you have 1200W PSU running at 20% load with 40% efficiency it doesn't really matter. Higher wattage PSU just means it can supply more wattage if the components need it.

 

[MMM]

Pretty much. Efficiency plays a role as well but unless you have 1200W PSU running at 20% load with 40% efficiency it doesn't really matter. Higher wattage PSU just means it can supply more wattage if the components need it.

I have read you stating efficiency numerous time on this forum with power usage.
Could you please supply all the power formulas and examples relating efficiency to your statements.

 

[Okedokey]

The energy savings you get from running a higher end efficiency PSU will never pay off the cost of buying that specificaiton in the first place.

I have read you stating efficiency numerous time on this forum with power usage.
Could you please supply all the power formulas and examples relating efficiency to your statements.

Efficiency calcs are pretty easy mate. Look at the specificaiton for the PSU under various loads and add the percentage to the required wattage. Ie. if the system requires 200W, it will pull 240W from the wall.

The cost of the OPs calculations are way way overstated. For example:

Tarrif: 22c/kWh
Operating Hours: 12 hours per day
Wattage : 185W
PSU efficiency: 72% (assume constant as I don't know the specifics)

So

Hours x Draw (W) from wall x Days /1000 = kWh from wall per year
12 hours x ((1 - .73)x 185W)+185W) x 365 days / 1000 = kWh from wall per year
= 1,030 kWh per year
$0.22 / kWh x 950 kWh = $226.40 per year (max)

Improving PSU effficency by 10% (e.g. better PSU with 83% efficiency):

Hours x Draw (W) from wall x Days /1000 = kWh from wall per year
12 hours x ((1 - .83)x 185W)+185W) x 365 days / 1000 = kWh from wall per year
= 950 kWh per year
$0.22 / kWh x 950 kWh = $208.57 per year (max)

So by getting a better efficiency PSU you save less than $18 per year, or $55 over a standard warranty period for a PSU (3 years).

The cost and savings proposed by the OP are exagerated in the extreme. Remember also, the above calcs are probably max wattage, unlikely to be sustained constantly for 12 hours per day.

To save money

• Enable hybernation
• Keep the computer cool
• Turn it off when not being used - including unplugging the psu (it will draw 30W when the PC is off).

 

[StrangleHold]

Efficiency in simple terms is the amount of watts being pulled from the wall vs. the output.

 

[MMM]

I was not really talking about cost of power as I assume you would purchase an energy efficient PSU in the first place.

You would try to have high efficiency PSU to gain the maximum output for your PC needs.

My understanding of Efficiency.....

Power supplies are for converting High voltage AC (alternating current) into low voltage DC (direct current) for use by electronic circuits etc etc.

Power supplies have a efficiency rating which determines how much useful power it delivers eg/
100 watt PSU has efficiency rating of 70% means it will deliver 70 watts at peak wasting 30 watts generally in the PSU circuit as heat....

Thanks bigfella for your response as I do understand those calcs you gave as I am an electrician, a little bit rusty on them as do very little these days.

This is what the electrical formula I was talking about, apparently some people here on the forum have different understanding.

 

[Okedokey]

I was not really talking about cost of power as I assume you would purchase an energy efficient PSU in the first place.

You would try to have high efficiency PSU to gain the maximum output for your PC needs.

My understanding of Efficiency.....

Power supplies are for converting High voltage AC (alternating current) into low voltage DC (direct current) for use by electronic circuits etc etc.

Power supplies have a efficiency rating which determines how much useful power it delivers eg/
100 watt PSU has efficiency rating of 70% means it will deliver 70 watts at peak wasting 30 watts generally in the PSU circuit as heat....

Thanks bigfella for your response as I do understand those calcs you gave as I am an electrician, a little bit rusty on them as do very little these days.

This is what the electrical formula I was talking about, apparently some people here on the forum have different understanding.

Please never let me let you loose on my electrical circuits as although you are an 'electrician' your basic understanding of efficiency, and maths evidently is flawed.

Efficiency in the formula you are referring to is based on mass balance. Fine for a heat pump, thermodynamics or where work or energy transformation is a direct function. PSUs are reactive therefore don't work that way. A 100W PSU with 70% efficiency does not deliver 70W as you suggest. Basic, basic mis-understanding. Absolutely astounding that an 'electrician' could make such a fundamental error.

A 100W PSU at 70% efficiency will still deliver (at a given temperature) 100W DC but draw 130W AC from the wall by doing so. Otherwise there would be no cost implication and efficiency curves would be linear (which they're not).

 

[FuryRosewood]

Suggestions above work...enable power saving features, keep the dust out, and if your concerned, just turn off the power strip when your not using it.. tho older hardware has no power saving measures, and i have seen cases where those units can pull almost 50 dollars a month due to that :/

 

[bratsos]

About electric bill, in greece and basically in europe (europe main power supply is oil and carbon...) is overpriced.
USA thanks the oil from Iraq have solve for 30 years this trouble... and bring the loser europe to economic crisis
And about old PSU from old machines, no worth to make any upgrade to that machines...
And when you play a high-end game into a low computer, computer using 100% of PSU... (CPU anf GPU load 100% and many others objects from desktop start asking for a 100/100% energy food)...

 

[MMM]

Please never let me let you loose on my electrical circuits as although you are an 'electrician' your basic understanding of efficiency, and maths evidently is flawed.

Efficiency in the formula you are referring to is based on mass balance. Fine for a heat pump, thermodynamics or where work or energy transformation is a direct function. PSUs are reactive therefore don't work that way. A 100W PSU with 70% efficiency does not deliver 70W as you suggest. Basic, basic mis-understanding. Absolutely astounding that an 'electrician' could make such a fundamental error.

A 100W PSU at 70% efficiency will still deliver (at a given temperature) 100W DC but draw 130W AC from the wall by doing so. Otherwise there would be no cost implication and efficiency curves would be linear (which they're not).

I made an error in my statement of the efficiency as you pointed out as my reference came from this article, but then again you should read it.

http://www.silentpcreview.com/article28-page2.html


No need to be sarcastic in your response about my qualifications as I stated a bit rusty on this as the last time I ever did efficiency & calcs was trade school days and in my field of work it is never called upon.

I apologize for not being perfect.