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Questions about PSU output

post #1 of 15
Thread Starter 
If a PSU has a max output of say 480w with an average output of 330w will the PSU provide more than 330w if needed?

For instance...if a rig needs 360 watts at peak would a PSU rated at 330 average provide the appropriate amount of power (assuming the max for the PSU is listed at 480w)?
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post #2 of 15
Yes, but it depends on the quality of the unit. Going beyond tolerances is not advisable for cheap PSU's for long periods.

Here's some information that may help you understand things a little better:-
http://compreviews.about.com/od/cases/a/PSUWattage.htm
Edited by Mhill2029 - 12/6/11 at 9:05am
 
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post #3 of 15
Thread Starter 
I suppose I would ask what the true tolerance of the example PSU is assuming its good quality.
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post #4 of 15
It really depends on the quality of the unit.. most(if not all) high end units can output well beyond their rating and will still provide very good regulation and output quality.... take the best PSU on the market today, the HCP is rated at 1200W, but in that power envelope every spec is so close to perfect that it's obvious it can do a lot more than it's rated for without going out of spec.. if you take a value unit for example, one that barely keeps voltage or ripple in spec at full load, you can expect it to go out of specification if it's overloaded... depending on the protections implemented and on the electronics(how over specced they are) some units can deal with insane overloads(50%!) without any issue whatsoever wink.gif

Most high end units are rated well below their capabilities to keep them in 80+ efficiency margins.. in other words, you can look at at HCP 850W as being a Silver rated 1100 unit smile.gif.. or you can look at the Kingwin Lazer Platinum 550W as being a Gold 650W unit or a silver 750W unit.. neither of these units would be hurt if they're constantly kept above they're rating, the only thing that would suffer is efficiency(you'll drop a few percents) and they'll sustain some minor drops on the overstressed rail/rails.. but they'll still behave A Lot better when overloaded than most value/mainstream units behave under 50% load wink.gif

^That more or less the reason for buying a high end unit... otherwise buying a HCP(for example) to keep it @ 50% load is nonsense and a waste of money, no point in paying a premium for such PSUs if you're not gonna' take advantage of what they have to offer wink.gif
Edited by Original Sin - 12/6/11 at 9:34am
post #5 of 15
Thread Starter 
Thanks to both of you. Both replies were helpful so...have some rep thumb.gif
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post #6 of 15
If a power supply claims a "max" or "peak" rating of 480W and then in small print lists its real wattage as "330W"... you can probably safely assume it to be a garbage 250-300W crap unit with completely false specs.
post #7 of 15
Thread Starter 
Thanks Phaedrus! biggrin.gif
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post #8 of 15
Thread Starter 
Also, if you have a PSU with multiple 12v rails rated at say 18 amps (say 12v X 2 at 18amps a piece) and a video card that requires 35 amps on the 12v rail do you add both rails to get a total of 36 amps thus being able to power the card properly or is that super far from whats actually going on....

As you can tell I'm quite clueless!
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post #9 of 15
Quote:
Originally Posted by Phen1863 View Post

Also, if you have a PSU with multiple 12v rails rated at say 18 amps (say 12v X 2 at 18amps a piece) and a video card that requires 35 amps on the 12v rail do you add both rails to get a total of 36 amps thus being able to power the card properly or is that super far from whats actually going on....

As you can tell I'm quite clueless!
That's actually pretty far from "what's actually going on".. it's more complicated than that..

A graphic card that alone requires 35A(420W) it's either a GTX 590 or HD 6990 and you shouldn't be putting either of those on a PSU with two 18A rails(432W combined 12v output at best) wink.gif
post #10 of 15
Thread Starter 
I guess what I'm driving at is this (It's a wattage question of sorts and yes I have used Phaedrus' calculator wink.gif ) I just got an awesome deal on a HD 5830 and I've been researching what PSU I need to power my rig with this new addition. I imagine I'll need 500+ watts but something I read suggested a psu with at least 35 amps on the 12v rail. SO i'm trying to figure out what i need on each12v if I get a psu with multiple 12v rails or what I need on the the 12v if I get one with a single 12v rail.


So basically I've just wound up in a state of utter confusion hehe...
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