When do you need more than one 12v rail on a power supply?

[tygasp]

Hi, I was looking for a power supply, around 600 or 700 watts, I planned on having just one better graphics card, two hard drives, about 6 140 led fans and a 250 mm led fan, and 2 DVD drives. So I need to know if I need more than one 12v rail for that, or not, and I would like to know when multiple 12v rails become necessary. Thanks for anything that you can tell me.

 

[clutchc]

That is a topic that will get both the single rail camp and the multiple rail camp going at each other. Each side will have a reason why their theory is correct. I advise that you read this short explanation from an expert on the matter:
http://www.jonnyguru.com/forums/showthread.php?t=3990

 

[tygasp]

Best answer selected by tygasp.