Tagan 530w - U22 - weak 12v rail?

[grungeisdead]

Right just bought this pc for my dfi board...

i dont have much in this system at the moment

3 x sata hds

x800xl

venice 3000

1gb ocz vx pc3200

the pc isnt overclocked at the minute.. i was just checking out my rails and im not sure whether they are in spec...

because this is the 2force edition i can select between 2 x 12v rails @ 20amps each for atx v2.0 or combined 12v rails for 40amps atx v1.3

ive got it on the split at the moment

idle

3.3v - 3.28

5v - 5.00v

12v - 11.84v

load

3.3v - 3.28

5v - 5.00v

12v - 11.78v

id surely expect this to be getting closer to 12v's than it actually is...

or should i be happy...

my pc has been running fine with a generic 400w power supply that has been rocking since rocking in various overclocked systems

 

[K404]

Are you sure that the combined rails give 40A? The current output of the rails (I think) depends on how the other rails are loaded at a particular point. There will always be a little loss on a loaded rail, I think the voltages are ok. I wouldnt worry about the output of the PSU until you hit an overclocking barrier that isnt down to any of the other components

Kenny

 

[grungeisdead]

no my bad its 32amps just had a look at the box...

but yeh my 400w generic psu had a tighter variance on the 12v rail and it was only 18amps... plus it was a 20 pin badboy on this dfi board...

cheers anyway mush... and you kenny should know more about psus than all of use since youve tried most of em out in the last coupla months

 

[K404]

Thanks for the vote of confidence!

32A sounds right, yea- rings a wee bell from the data sheet I had a look at. I`ve learned that the combined rails give a current less than the merged rail because the extra current doesnt "exist" anyway...

If each rail can provide 20A, but combined gives 32A, 8A have gone walkies. This 8A never exists- if one rail is delivering 20A, the other can only supply 12A Tagan (and a lot of other manufacturers) play at out-speccing the competition. Remember my post about the ampages and wattages not adding up? The same thing (in part) was happening there. There were losses, sure, but the "bigging-up" that Tagan did was absorbed in there too.

As for the undervolting... the +12V potential difference will only apply when there are 2 wires, open-circuit. one is 12V higher than the other. Ideally, one wire is at zero (ground) but not always.

When a load (anything) is connected between the wires, the properties of the components between them will change the potential difference between the 2 wires. Loading the CPU will change the current draw, and change the way the load is seen by the wires, to have a difference of 0.06V on the +12V line between idle and load is pretty damn good (IMHO!)

Kenny