Will i be charged 1KW/H per hour for idle comp if 1KW PSU???

[DaRAGEr]

If i had a 1000 watt power supply, that could supply those 1000 watts, but just say the computer is idle... Will i get charged 1KW/H from the electricity ocmpany per hour the computer is on idle, or only if the hardare is using up a full 1000 watts will i get charged?

For instance if the computers idle and only using just say 300 watts, then will i get charged 300 watts/hour or 1KW/H due to having a 1KW PSU?


Is that why it's better to get a more efficient PSU?

Help me Obi Wan Kenobi

You're my only hope.

 

[twanto]

1000 watt PSU means that it can handle that much, but it won't necessarily draw that much. Depending on efficiency, your computer will use about 70-80% of what the unit draws. What it draws depends on what your computer is doing. At full load you probably will not draw 1kW unless you light your house with it.

 

[altazi]

Twanto nails the idea that your computer will use different amounts of power, depending upon what it is doing.

The power company doesn't have any idea that your computer has a 1kW-capable PSU, nor do they care. All they care about is the amount of power used that registers on your wattmeter outside your house. Whatever the power consumption of your computer, it will be counted by the wattmeter. If you are using 300W/hr, that's what it will tally. If you are cranking in SLI on an intense game, and hitting around 700-800W/hr, the wattmeter will tally that, too. You use more power, the electric company gets more of your money.

The reasons to get an efficient power supply, IMO: less wasted power = less wasted heat dumped into your room environment = less money wasted on electricity bill. Also, higher efficiency typically means better power supply design, less stress on components, and just that "green" feeling

Altazi

 

[aevm]

You've already good great answers there. Just my two cents: a larger PSU will actually cost you LESS every month than a smaller PSU, simply because the larger PSU will stay in its area of optimal efficiency more often than the smaller PSU. For example, a 1000W PSU will result in smaller electricity bills than a 520W PSU if the PSUs are of comparable quality and your PC usually needs around 500W. Here's a sample chart:

http://anandtech.com/casecoolingpsus/showdoc.aspx?i=3040&p=11

Of course, the difference won't be huge. Say, getting 85% instead of 75% for an hour a day and the same thing the rest of the time will save you only a buck or two a month. It's not worth paying $300+ for a huge PSU unless you actually need all that power. For example I got myself the 750W PSU reviewed there and it's plenty even for Q6600/8800 GTX OC2 and up to 7 hard disks.

 

[EpIckFa1LJoN]

You have to take into account efficiency above everything else. ALL PSU's regardless of rating plummet under 20%. The Corsair AX1500i even which is an 80 PLUS Titanium rating nose dives from an optimal efficiency of 95% at about 750W down to 90% at 10% utilization which is 150W, basically most high end computers at idle. Now 90% efficiency is still VERY good, but you can also do better for cheaper.

For example I am looking at either the AX760i or the AX860i, both are 80 PLUS Platinum and both have very high efficiency ratings in the range I will be using. I am still going to get between 91-94% efficiency at a much lower price than the extremely high-end AX1500i.

So my computer while gaming uses approx. 300-400W which with the right PSU I should get about 94% efficiency, meaning per hour of gaming I am drawing about 320-425 W/hr, I pay about $0.09 per kWh, so it would take me about 30 hours to spend $1 in power. At idle its more like a 120W draw, but with the PSU efficiency going way down due to under-utilization, probably about 85% on mine, more like 140W, at idle I could literally keep my computer on all week at idle and spend maybe $4.

Now that sounds really fishy to me but that's the math I come up with. I'm sure someone will correct me if I am wrong but I think this is accurate.

Now if you get a really sh**y PSU and you are getting like 80% efficiency at your load, say you are running SLI while gaming, probably looking at 500-600W, at 80% efficiency your consumption is 600-750 W/hr. In other words you're still not paying a ton in electricity to run your computer but you are spending roughly 12% more on power than you would a better PSU. It's really not a lot it would take months for you to notice the difference in a 750W 80 PLUS Bronze and a similar PSU with 80 PLUS Platinum.


But in short, no you are not going to be paying 750W/hr if you have a 750W PSU, you only pay for what you use, and efficiency is a big factor in that.