Q: If i remove a PSU from an old PC Tower. Plug it in, not connected to anything else, throw the switch, should the fan start up, or does it have to be connected to the mobo HD etc. I'm just trying to find out if its working or not Thanks to my first answer, but thats not what I really wanted to know lol Thanks Tay & Ron a: I dont know what a processor is b: you say it may not start fully. Well it shows no sign of life. Not a peep
A: sewrobb is wrong, unless he means only the old AT power supplies. An atx PSU will not start unless the power on pin 14 (normally green) is shorted with any ground pin (usually black). This happens when you plug it into the motherboard. You can use a piece of wire, paper clip or similar to short these two pins and plug in and switch on the power supply to see if it is working. Do this at your own risk. Check your particular supply for accurate information on the power on and ground pins. The link below shows how to short the pins for testing.