Flying Fox wrote:
Also a lot of these multi-12V rail PSUs actually have just a single 12V source anyway. So as long as their combined output is enough you are ok.
Most of the multi-rail stuff is standards compliance. The rails are split so that if one goes down the devices connected to it go down as well, rather than sucking power from the remaining rails. ATX standards compliance requires this because the 12ga wires used in the PSU leads are rated for 20A maximum. The 60+A single-rail PSUs are capable of sending all 60A down a single 12ga +12V wire, which is triple the current it's rated to carry. Granted, a failure chain that results in a single +12V lead being asked to carry all +12V requirements is damn near impossible, but electrical codes don't have wiggle factors.