How do I power up a car stereo using a power supply from a computer?

I don't think it will work (though I may be wrong but I think not) because computer power supplies are switching power supplies, IOW they don't just give 5v and 12v outputs regardless of all other factors, those wires in the plug that goes to the mother board have to have inputs that tell the power supply it's okay to give the other components their voltage. Maybe you have another 12volt power supply around the house that can do it, many 12v "wall warts" have enough current to get it to at least turn on. It's entirely possible to use a PC power supply by using jumper wires across certain pins, though I'm not sure, nor do I know which pins to short. Obviously you could experiment, make sure you don't REALLY need the power supply and have a fire extinguisher ready. ... more