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Proper PSU power distribution...

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Dark Prodigy

Jawbreaker
Joined
Mar 10, 2006
Messages
2,803
Ok, I need to understand a few things and hopefully some learned users will help me.

As I currently understand it (I could be very wrong here), certain peripherals should not share rails, no matter how powerful the PSU. In every system there are HDD's, optical drives, video cards (most) etc... my question is there a 'proper' way to distribute devices on a PSU for better stability.

I currently have a dual core CPU, 2 video cards SLi'd, 3 HDD's including raided raptors, 3 HDD coolers, fan controller, 2 optical drives, audio I/O header, water cooling pump, 4 fans, motherboard EZ Plug, 2 12" cold cathodes and some other stuff I've probably forgotten; basically a typical system for [H] members. Of course all these things are required to be plugged in. The problem is that there are more devices than molex connectors, so we have to buy splitters.

In trying to power everything, should certain devices on a particular rail not 'share' its power on that rail from the PSU? Like 2 video cards on 1 rail and that rail shared with less power consuming devices such as fan controllers and cold cathodes. Or all HDD's on 1 power rail and that rail split with the opticals drives...What's the limit on 'splitting' rails if there is one. And are my speculations founded or am I thinking too much.

Power hungry devices such as video cards should not share the same rail with anything.. What devices are safe to share power with. Or should I ask just how far can I split or branch a power rail and with what device types.
 
Dark Prodigy said:
Power hungry devices such as video cards should not share the same rail with anything.. What devices are safe to share power with. Or should I ask just how far can I split or branch a power rail and with what device types.
Click to expand...
You'll run out of rails if you do that. You want only one high-draw device (video cards and CPU) per rail whenever possible, and divide all of your accessories (drives, pumps, fans) as evenly as possible.

Triple rail PSU powering SLI:
1st rail: Motherboard/CPU, maybe pump if water cooling
2nd rail: 1st video card, some drives
3rd rail: 2nd video card, some drives

Most PSU's will have the first rail dedicated to the motherboard. In that case, just split the load across the rest of the rails.
 
Dark Prodigy said:
Anyone else have any theories?
Click to expand...

There are no real theories as it all varies based on the PSU's topology...... which was supposed to be covered under the ATX12v and EPS specs so this wouldn't happen but the ATX 12v spec hasn't been updated in so long companies have started severally deviating from it. So you have to look at each individual units topology and figure it out on a case by case basis. That is part of the reason I put the rail breakdowns in all the multi12v rail reviews.
 
I prefer the single rail psu.. You don't have to worry about power distribution with them, as long as it has the amps to cover what you are powering..
I am running a Silencer 750.. It only has one rail, and everything works fine..
 
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