PSU rails

[Bob The Builder]

Is it better to have a psu with just one rail or multiple rails? I read in a magazine that with the multi-rails, if one rail is overloaded that the whole psu can go bad and possibly burn down the whole pc. Is there different connectors for each rail? For instance: psu's come with multiple connectors, so you plug in your GPU/card to one, hdd's to another, optical drive to another and so on. Does each connector correspond to a seperate rail, so you would know if you were going to overload the rail?

The single rail has all the power to the rail at all times and won't get overloaded unless you didn't have enough juice to begin with. Am I getting this right? Someone help me understand. I am in the process of getting my parts list together to build my first PC and want to get it right the first time!

 

[Kornowski]

I'm not entirely sure if it's better to have one or the other, but I think the multiple railed PSU's are better.

There are no different connections for each "rail". But, Like you said, there are different connections for the different parts of a computer, like Fans and DVD Drives will use 4 Pin Molex Connectors. SATA HDD's will use a SATA Connection, Graphics Cards will use a PIC-e Connection & the Motherboard will use a 24Pin Connection and a 4 / 8 Pin Connection.

No brainer really, if it doesn't fit, it's not meant to go there

 

[ceewi1]

Is it better to have a psu with just one rail or multiple rails? I read in a magazine that with the multi-rails, if one rail is overloaded that the whole psu can go bad and possibly burn down the whole pc.

That's not true. If any individual rail is overloaded, the PSU will immediately shut off.

Is there different connectors for each rail? For instance: psu's come with multiple connectors, so you plug in your GPU/card to one, hdd's to another, optical drive to another and so on. Does each connector correspond to a seperate rail, so you would know if you were going to overload the rail?

The exact arrangement differs from PSU to PSU. In most dual rail designs, the CPU is on one rail and everything else is on the other. In designs with more rails, the connectors are split up further (e.g. CPU on one rail, 2 PCI-E connectors on a second rail, all peripheral connectors on a third). There is not really any consistency between manufacturers for how these are split up, but unless you have very unusual power requirements, most any well designed modern PSU will not have any issues with this rail distribution.

The single rail has all the power to the rail at all times and won't get overloaded unless you didn't have enough juice to begin with. Am I getting this right?

Yes, that's correct. As I said, though, overloading any individual rail is unlikely to occur on most modern PSUs.

There are arguments in favour of both single and multi-rail designs. Single rail units cannot have rail distribution issues, while compliant multi-rail PSUs have an added level of safety in preventing any single component to draw more than 20A if short circuited, which could otherwise damage the wiring.

In the vast majority of cases, however, single rail vs multi-rail is a non-issue. I would not base a purchasing decision on it.

 

[Bob The Builder]

In the vast majority of cases, however, single rail vs multi-rail is a non-issue. I would not base a purchasing decision on it.

Then what would I base the criteria of the PSU I would consider? What is it that makes a good PSU? What brand? What model? What watt?

Basic set up:

Asus P5K MotherBoard P35
Intel Q6600
WD 640 GB
NVidia 8800 GT-ish (probably never SLI)
2GB DDR2 800 RAM
Asus DVD-R Dual Layer
XP/PRO or Vista (32/64 bit?)

 

[mep916]

Then what would I base the criteria of the PSU I would consider? What is it that makes a good PSU? What brand? What model? What watt?

Read through the PSU guides...

http://www.computerforum.com/computer-cases-power-supplies-cooling/announcements.html

Basic set up:

Asus P5K MotherBoard P35
Intel Q6600
WD 640 GB
NVidia 8800 GT-ish (probably never SLI)
2GB DDR2 800 RAM
Asus DVD-R Dual Layer
XP/PRO or Vista (32/64 bit?)

I'd go with at least 500W.