Ok so then why do so many people go into a big trouble of modding their ATX power supply when they can use the molex connectors as their power supply?? for example:
YouTube - Converted Computer ATX Power Supply to Lab Power Supply Unit
I don't really understand your question. The volatge will always come from the ATX power supply. The connectors do not become the power supply if you hook up circuits through them as opposed to clipping them off an just using the loose wires. I don't know why that particular person in the Youtube video decided to modify his power supply that way. He didn't change or "convert" it from how it would normally operate by simply connecting all the like outputs. Maybe he just thought it would be easier to hook things up to it if the outputs were tied together as opposed to having to pin out from the connectors. Whether or not you clip off the connectors as shown in the video or keep them on and stick pins into the appropriate sockets has no effect on the voltage that is being supplied.
That's assuming that all you have to do is short out the one of the pins so that the ATX thinks it is still connected to a computer...
I'm not sure if it's OK to just short out one of the pins to place a load on the power supply and keep it from turning off. Maybe someone else can chime in about that. I modded an ATX power supply a few years ago that I used to power a pump and I placed the load on it by soldering a 10Ω power resistor between one of the 5V outputs and ground.
I really don't want to fry my electronic components so i'm just asking if it's safe to hook up a 12V line from one of the molex connectors to my breadboard and use it as a power supply.
I thought I answered this in my last post but I'll try again.
The power supply provides a voltage. The current that is allowed to flow at any given voltage depends on the resistance of the load attached to it. If you are having trouble understanding that concept go read
this.
I cannot tell you if it is safe to hook up a circuit or a component to a 12V supply without knowing what that circuit or component is. No one here can. Some circuits will do fine if you apply 12V to them. Some will fry. Some will not have enough voltage and won't work. Your question is not specific enough.
Imagine if you went to the store to buy a tire for your car and you told the guy there "I want a tire". He then asks, "what kind of car do you have", to which you reply "I don't know". The guy will not be able to tell you if a particular tire will work or be safe with your car because he has no idea what kind of car you will be attaching it to.
What your asking is kind of like the tire analogy. Whether or not it's safe to hook up 12V to your breadborad or not totally depends on what circuit is in the breadboard.
If you know that it is OK to apply 12V to a given circuit, it doesn't matter if that voltage comes out of the connector or, if you remove the connector and hook up the loose wires. The electrons don't care.