Originally Posted by smoke12291
possibly an example with easier numbers to explain something to a noob?
Let's see if I can explain it better.
Take PSU 1:
Single 12V rail design
True Dual 12V rail design (imagine 2 500W PSUs in the same case together providing 1000W)
A quality 500W PSU is pretty easy to make. The parts needed don't need to be all that special. It's kind of like building a car that can go 100mph or building one that can do 200mph. The 100mph car is typicaly much more simple, easier to make and cheaper. You don't have to have a lot of horsepower or tires and suspension that can handle 200mph. The 100mph car is much cheaper and easier to make even if the cars have similar acceleration up to their top speed.
So by that, PSU 1 needs to have very high quality parts to be able to provide 1000W adding costs and complications. Since it is much to easier to make a 500W, putting 2 together in one package to reach 1000W (PSU 2) is cheaper and much easier to get similar or better performance as PSU 1.
Originally Posted by clbkdaz
Heck - do they still limit each rail to 20a?
EPS 12V standard (which is what multi-rail PSUs are designed to adhere to) says the limit must be 18A for each connector. Most companies typically just go with 18A per rail and stick one or two connectors on it (PCI-E, CPU 12V, etc...).Edited by shinji2k - 6/27/08 at 7:59pm