Power Supply draw questions.. help!

srsanborn

Member
Jul 29, 2001
27
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This is a "wiring theory" question dealing with how power gets pulled from the PSU down each chain of power connectors.

OK, so here's my scenario: I'm using a 480W to power 4 HDDs, 2 CDroms, a memory card reader, 5 fans, and a UV cathode (not to mention mobo and misc. PCI cards but that's besides the point). Due to my layout, I have a lopsided wiring arrangement, one of my wires goes to 2 CDs and UV, one goes to 3 HDDs, and one goes to 1 HDD, memory card reader, and 5 fans.

I've been getting some problems with the 1 HDD on that string, which were alleviated when I unplugged a few of the fans (apparently due to excess draw down the line, since it has like 3 Y splitters) My question is - do all these wires pull from the same common "pool" of max power output from the PSU, or does each wire get a certain percentage of output?

In other words, if my components pull say, 300W, and I plugged them all onto one string with a ton of Y splitters, would that be the same as using 3 strings like I am now? Or is my excess power draw problem on that string due to splitting it too many times .. and would putting a couple fans on each string be better for the overall power draw?

Does anyone have documentation on how power gets pulled from any given PSU, or perhaps tips on effectively wiring for a "large" system consisting of many drives and many fans? (Like putting a few fans on each chain as opposed to all of them on the same, etc etc).

Any help is appreciated...
 

Zepper

Elite Member
May 1, 2001
18,998
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Except on some expensive PSUs, all the current for the positive voltages comes from the same pool. 1-3.3V pool, 1-5V pool and 1-12V pool which all feed off of various windings of a high freq/votage tranformer. So you want to try to divide the load as evenly as possible among the various strings of connectors.
.bh.