Ps on could be either a command to turn on the supply, or a o/p to say that thesupply is actually on, mete itand see if it changes state when you try to power up the unit, see what happens, if it goes to an ic see if you can get the datasheet for the ic and from you might be able to find out if its a i/p or an o/p.
Dont run without the 'sink, have you seen a intel chip without a sink, kaboom, this might not happen with your circuit, but it certainly isnt adviseable.