-=PCTechTalk=- Re: Power Supply

Power in WATTS is equal to Amps times volts.  So the two 12 volt rails 
share the 552 watts.  I don't know how they get that figure since 12 x 
25 plus 12 x 25 equals 600.  If you add the 5v + 3.3v times 25 amps you 
get 207.5 watts and then  the -12 at .3 amps is 3.6 watts plus the 5vSB 
at 2.5 amps for 12.5 watts everything adds up to

600
207.5
   3.6
012.5
---------
823.6 WATTS.

I assume that is max peak wattage and the 700 watts number is more like 
a normal or continuous load.

I gather from your comments that most common devices in a computer use 
the 12v rails.  I will eventually have a SATA BlueRay player and a nice 
single video card with HD capabilities added to the existing SATA DVD 
burner, USB card reader, 500GB and 160GB SATA hard drives.

Since it is unlikely that both opticals would be in use at once I figure 
the mobo and a hard drive on one and the other harddrive and both 
opticals on the other. There is no floppy.

I assume those other voltages are for things like the video card and 
will likely have no concern about balancing the load across them????

What else might be put in a computer that would I would need to concern 
myself over what rail to put it on?

Don




Gman wrote:
> The number of rails refers to how the +12v supply is broken up.  A single 
> rail design will have all of the +12's on the same circuitry, but a 4 rail 
> design will split up the +12's maximum allowed amps across 4 different 
> circuits.  From your description, it looks like it has 2 rails (The second 
> section has two +12v outputs rated at 25 amps each and 552 watts) splitting 
> 50Amps across the two evenly.
>
> When you go to connect everything, you'll want to divide your +12v devices 
> between the two leads coming out of the PS.  So, if you have two hard 
> drives, the mobo's +12 and maybe a floppy drive, you can put the floppy and 
> mobo on one lead and the two hard drives on the other.  If you also have two 
> optical drives, put one of them on the first lead and the other on the 
> second to help distribute the power more evenly.
>
> On the other hand, if you have any one device that requires more power than 
> most, it may force you to include less additional items on that lead.  Look 
> carefully at the requirements of all of the devices that require +12v power 
> and work to balance them as well as possible between the two leads.
>
> The +5vSB supply is one that is always on, even when the PS is in standby 
> mode.  It's used to power 'wake on ...' devices that allow the system to be 
> booted from across a network.  This supply is delivered to the system as a 
> part of the mobo connector, so it's not something you have to try and 
> identify when you're installing the PS.
>
> Peace,
> Gman
>   
>   
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