dual rail vs single rail

[nomnom123qwe]

i need to explain this to a friend as short as possible and i do not know the difference myself so can anyone explain which is better for a computer with gpu and cpu

[iamdarkyoshi]

think of duel rail as two seperate power supplies in the same box. If each rail can do say, 10A but the GPU pulls 12A and the CPU does 6A, then a duel rail would be useless as the GPU pulls more than a single rail can handle. However, say a single rail PSU can do 20A and it is running both the CPU and GPU (18A total), then it is under the maximum rating. Each would be rated at a theoretical 240 watts, but the single rail one can distribute it more effectively.

[Godlygamer23]

Dual rails refer to the +12V rail(s). Essentially, having a dual(or quad) rail design splits the total +12V amperage capability among four circuits. This can allow for safer operation because you're not forcing loads of power through a single rail. However, you also have the chance of overloading one of the rails and causing issues. That being said, some units combine rails into a single virtual rail to the user so that doesn't happen. Having multiple rails can also cause cable connectivity issues if the rails are separate to the user.

[Grrizz]

Personally I prefer to stick with a single rail for convenience but I'm also not running a 1000W+ PSU. This may be of interest to you: