Would a PSU with only 1 12v rail cause any problems?

[TheSpy007]

It has only 1 12V rail, +12V@49A. Would there be any problems with a psu with only one?

 

[Navid]

If everything else is the same and the only difference is single rail versus dual rail (for the same total max current and power), I would prefer the single rail.

The only disadvantage of the single-rail would be fire/spark hazard if you are not careful!
If the dual rail satisfies the ATX spec to the letter, it will clamp the current on any of those two rails to 20A limiting the power output on any of those two rails to 240W while the single rail could allow twice that much power. So an accidental short circuit in your system while working on it would generate a spark twice as powerful with the single rail PSU.

It gets really complicated though since first of all, not every dual rail PSU really satisfies the spec to the letter and secondly, there are no two identical PSUs with the only difference being the number of rails. There are always many more parameters that are different between two power supplies.

 

[Navid]

Some say that having more rails allows you to isolate sensitive components in your system by running them off different rails. What they seem to forget is that there is no sensitive component in a PC that is directly powered by the 12V rail. For example, you may say that the CPU is powered from the 12V rail through the 4-wire cable from the PSU. Well, that 4-wire cable really powers the CPU voltage regulator. The CPU is powered by a 1.5V supply not a 12V supply. The voltage regulator that converts 12V to 1.5V provides significant isolation between the CPU at 1.5V and the 12V rail. So, there is enough isolation in the system already.

 

[Howard]

Nothing wrong with single-rail PSUs whatsoever.

 

[JEDIYoda]

Originally posted by: Navid
If everything else is the same and the only difference is single rail versus dual rail (for the same total max current and power), I would prefer the single rail.

The only disadvantage of the single-rail would be fire/spark hazard if you are not careful!
If the dual rail satisfies the ATX spec to the letter, it will clamp the current on any of those two rails to 20A limiting the power output on any of those two rails to 240W while the single rail could allow twice that much power. So an accidental short circuit in your system while working on it would generate a spark twice as powerful with the single rail PSU.

It gets really complicated though since first of all, not every dual rail PSU really satisfies the spec to the letter and secondly, there are no two identical PSUs with the only difference being the number of rails. There are always many more parameters that are different between two power supplies.

there really is NO disadvantage to having a single rail. At all!
What you are saying is at best based on conjecture and event that do not normally happen at all!!