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PSU power consumption.

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January 26, 2011 7:14:20 AM

Will a computer with a 500W PSU use as much electricity as a computer with a 750W PSU and the same components. I am asking this because I don't know what PSU to get for my new build. I know that I will not need such a big PSU as 750W, but will need it in future when I will be putting to graphic cards in a crossfire setup. The thing is, I am not sure if I should get a 750w psu straight away or should I get a smaller PSU and upgrade it whenever I get a second graphics card. Thanks In advance.

More about : psu power consumption

January 26, 2011 7:45:48 AM

Tell us what PSU(s) you have in mind, give us your specifications too please.
January 26, 2011 8:17:26 AM

Here it is

CPU (will be overclocking it to about 3.8-4.0 ghz)
AMD Phenom II X4 965 Black Edition
http://www.ebuyer.com/product/186428


FAN
Cooler Master Hyper 212
http://www.ebuyer.com/product/245376


MOBO:
Gigabyte GA-890GPA-UD3H 890GX
http://www.ebuyer.com/product/197546


GPU:
HD 6950
http://www.ebuyer.com/product/250399

RAM:
G-Skill 4GB (2x2GB) DDR3
http://www.ebuyer.com/product/180490


HDD:
Samsung SpinPoint F3 500GB
http://www.ebuyer.com/product/146252


PSU:
Corsair 450W VX Series PSU
http://www.ebuyer.com/product/131052


OR
Corsair 750W HX Modular PSU
http://www.ebuyer.com/product/164950


So should I get the 750W corsair now and when I buy another hd 6950 i won't have to upgrade the PSU.
OR should I get the 450W corsair and upgrade it once I get another hd 6950. But the main question is will the same setup with diffrent PSU (450W and 750w) use as much electricity ?? ?


Related resources
January 26, 2011 8:26:35 AM

AtusSephin said:
Here it is

CPU (will be overclocking it to about 3.8-4.0 ghz)
AMD Phenom II X4 965 Black Edition
http://www.ebuyer.com/product/186428


FAN
Cooler Master Hyper 212
http://www.ebuyer.com/product/245376


MOBO:
Gigabyte GA-890GPA-UD3H 890GX
http://www.ebuyer.com/product/197546


GPU:
HD 6950
http://www.ebuyer.com/product/250399

RAM:
G-Skill 4GB (2x2GB) DDR3
http://www.ebuyer.com/product/180490


HDD:
Samsung SpinPoint F3 500GB
http://www.ebuyer.com/product/146252


PSU:
Corsair 450W VX Series PSU
http://www.ebuyer.com/product/131052


OR
Corsair 750W HX Modular PSU
http://www.ebuyer.com/product/164950


So should I get the 750W corsair now and when I buy another hd 6950 i won't have to upgrade the PSU.
OR should I get the 450W corsair and upgrade it once I get another hd 6950. But the main question is will the same setup with diffrent PSU (450W and 750w) use as much electricity ?? ?


The 750W HX will use less power than the 450W VX. See:

http://www.plugloadsolutions.com/psu_reports/CORSAIR_CM...

And

http://www.plugloadsolutions.com/psu_reports/CORSAIR_CM...

The 750W HX has around 88% efficiency at 25% load, while the 450W VX has around 84% efficiency at 50% load
a c 92 ) Power supply
January 26, 2011 8:46:33 AM

100% correct answer will depend on the models you're looking at. The answer depends on the load of the devices, and how efficient each PSU is at converting AC to DC. What you'll probably find is that at idle or other low power states such as surfing or watching TV/movies the 500W will consume less power. If you are doing a CF setup however you might as well get the 750W now. It won't cost you much more per year to operate it, and save you from having to buy another PSU.
January 26, 2011 9:43:54 AM

Thanks a lot !! Can be marked as solved :) )
a c 92 ) Power supply
January 26, 2011 9:45:41 AM

Doesn't work that way, you need to mark it as solved by picking the best answer.
a b ) Power supply
January 26, 2011 12:58:14 PM

(1) Pick a "GOOD" quality Brand and get one that is at least 20% > than ANTICIPATED max load. as longe as 80% eff do not sweat PSU wattage diff (ie going from a 650 -> 750 or 850 W

A diff of eff rating of 5 % and a true Power consumption of say 500 Watt.
500 * .05 x 24 hours per day at max load * 365 days * $.08 per KW/hr = $24.50 per Year and This is if you gamed 24 Hours per day every day of the year (real cost diff is only about $8 per year)

Repeat - Pick a "GOOD" quality Brand and get one that is at least 20% > than ANTICIPATED max load.
January 26, 2011 1:19:07 PM

how do i pick the best answer?
a b ) Power supply
January 26, 2011 2:50:02 PM

Response from randomizer in an older thread.
Quote
You can only select a best answer for threads that are Questions rather than Discussions or Polls. When you create a new thread there will be a red tab for each type that you can pick from. The best answer button will be in the lower right of a post.
End quote
January 26, 2011 7:01:53 PM

AtusSephin said:
how do i pick the best answer?
Eheh, with so many answers how to choose...

Anyway, those graphs I linked you to give you a fairly exact answer that indicates your 750W choice will "always" be a more efficient part than your 450W choice.
January 26, 2011 7:49:58 PM

All I can do is vote up or down on an anwser. Can't pick the best anwser even though it says that this is a disscusion with an awser. : S :??:  :??: 
January 26, 2011 8:28:52 PM

Quote:
Hope this will make it easier...


While I'm sure he appreciates ALL the various answers that tell him how much power he'll use, rules of thumbs, etc, he ask about two specific power supplies: The 450W VX and 750W HX.

And we have exact data for those two power supplies, via an indepedant testing lab, that shows that at all "realistic" load levels the 750W HX is more efficient than the 450W VX. It's just designed and made better. I don't think you can get a more direct answer than "the 750W HX always wins".
January 26, 2011 11:39:34 PM

Quote:
450<------------------------- no future upgrades in mind, smaller overhead
750<------------------------- bigger overhead with upgrades in mind. no need to shop for a psu again if you decide to add a 2nd card
Wrong, completely opposite. The 750W has smaller overhead, here again are the links:
http://www.plugloadsolutions.com/psu_reports/CORSAIR_CM...

http://www.plugloadsolutions.com/psu_reports/CORSAIR_CM...

I'm getting ready to tell this guy "ignore everyone and assume we're all wrong, then look at the data in those links yourself".
a c 92 ) Power supply
January 27, 2011 12:21:14 AM

Still spreading that incorrect list around Diggle?

Crash took the time to look up the efficiencies under load points, so if the HX is that much better then the VX it looks like I was wrong. I guess the question then becomes do you have the $$$ for the HX?
January 27, 2011 2:19:57 AM

4745454b said:
Still spreading that incorrect list around Diggle?

Crash took the time to look up the efficiencies under load points, so if the HX is that much better then the VX it looks like I was wrong. I guess the question then becomes do you have the $$$ for the HX?


Yes, the quality difference breaks the "rule of thumb" I've seen this before, too...I had a 750W power supply the dropped to something like 72% efficiency at 10W that I used in a low-power platform analysis. And the reason that I used it was because my smaller power supplies had a PEAK efficiency of about 72%. Efficiency is about design first, proper sizing second.
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