I wanted to know how to evenly distribute the load on my power supply? I have a corsair 1000w which has 2-12v rails at 40A each. According to the manual 4 pci-e connectors are on one rail and everything else, including two hardwired pci-e connectors, is on the other rail. Since I have two 4850's which require 1 pci-e connector each, I just use the hardwired ones. My question is should I use two modular pci-e connector that is on one rail for the video cards and let everything else go on the other rail, use one modular on one card and one hardwired on the other card, or do what I'm doing now which is use both hardwired pci-e connectors on each card. By doing the latter doesn't that mean that everything in my system is on one rail and essentially only have the potential of using 500w? Please help me understand how to correctly use not only my power supply but power supplies in general that have more than one rail
The Corsair HX1000 power supply takes care of power distribution for you. You don't need to do anything. Just use the correct hardwired video power cables
Two Radeon HD4850 video cards operating in dual Crossfire mode use a combined total of 220 watts and 20 amps at full load. The source of the information is a recent article about actual video card power consumption published here at Tom's hardware. A single +12 volt rail rated at 40 amps can easily handle those cards.
FIY - The Corsair HX1000 is also certified by NVidia for 3 way SLI mode.
Here is a link to a technical review of the HX1000 over at JonnyGuru.com: