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Advice needed please

andrei3333

Senior member
Jan 31, 2008
449
0
0
So i have a friend for whom i built an i7 system recently, and two months later he decides to start gaming, go figure, anyway his PSU will not cut it and he needs a new one, the manager of the store where we bought all the bare parts agreed for an exchange of his current 500w 18A/rail supply for something with more punch

the video card he just picked up is gtx560ti -- it requires 30A on the 12Vrail. its a standard PC with no fancy stuff.

Question: i havent researched psu's in a while and i need to help him get one tomorrow, i see there are psu's rated at 500 watts that meet the vid cards min 30A rating, and then i see 600 and 700 watt supplies that dont cut it at 25A/ rail

what am i missing here ? what psu is needed here ? he is on a pretty tight budget btw
will this do the trick ?
http://www.tigerdirect.ca/applications/searchtools/item-details.asp?EdpNo=422166&body=MAIN
Thanks
 
Last edited:

theAnimal

Diamond Member
Mar 18, 2003
3,828
23
76
Question: i havent researched psu's in a while and i need to help him get one tomorrow, i see there are psu's rated at 500 watts that meet the vid cards min 30A rating, and then i see 600 and 700 watt supplies that dont cut it at 25A/ rail

what am i missing here ?

The total 12V amperage is what the recommendation is for, not just a single rail, and the total is usually lower than the sum total of the rails. Quality also matters since high quality PSUs will be able to stably deliver their rated power.
 

Meghan54

Lifer
Oct 18, 2009
11,684
5,228
136
the video card he just picked up is gtx560ti -- it requires 30A on the 12Vrail. its a standard PC with no fancy stuff.



Remember, that amperage recommendation is a SYSTEM WIDE recommendation, not just the video card. And those recommendations tend to be high to account for the crap power supplies out there that basically lie about their +12V output.
 

lehtv

Elite Member
Dec 8, 2010
11,897
74
91
The total 12V amperage is what the recommendation is for, not just a single rail, and the total is usually lower than the sum total of the rails. Quality also matters since high quality PSUs will be able to stably deliver their rated power.
Remember, that amperage recommendation is a SYSTEM WIDE recommendation, not just the video card. And those recommendations tend to be high to account for the crap power supplies out there that basically lie about their +12V output.

This and this.

The original 500W PSU might be good enough, just need to know manufacturer/model
 

andrei3333

Senior member
Jan 31, 2008
449
0
0
He exchanged it for a coolermaster unit with 700 watts and a 52A rating,

yes - overkill, but it was only $20 more then the one he already bought,

so just for the future - what do you guys mean total amperage? the current is divided in parallel between the 12v rails isn't it ?
 

theAnimal

Diamond Member
Mar 18, 2003
3,828
23
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The total amperage that the video card recommendation refers to is for power consumption of the entire system, not just the card. That number is supposed to be lower than the total amperage listed on the PSU (not just by adding the rails, which in the case of that Cooler Master would give 76A).