One of those requirements is that SOME form of load must exist on each output for proper voltage regulation to occur. Usually the 5V line is the most important source to have a constant load on. This is usually done with a BIG power resistor of low value.
I get 5.12V on most of my pc supplies just measuring with my mulitmeter which is well within the range of most 5v components (5.5v max standard)
Mowcius