Power supplies

Absolutely! They're a great source of smooth filtered power. In fact I have 'em on my desks at home *and* at work wired up for experimentation. There are a few caveats, though. To get more recent ones (the ones which can be switched by the motherboard) to turn on, you'll have to tie the green wire on the motherboard connector to one of the black wires, either through a switch or just solder them together and use the wall power to turn them off and on. Switching power supplies have a minimum current they need to stay on. Usually you have to draw at least half an amp, sometimes as much as an amp and a half, from the main +5v power supply to keep 'em running consistently. Either a decent incandescent lightbulb (4 cell flashlight battery), or a big honkin' 8 to 10 ohm resistor (appropriately sized, that's several watts so one of those ceramic 25 watt bricks that Radio Shack sells, and watch out for heat!) between a black and a red cable will do good things for you. Switching power supplies also work by charging a capacitor and then sampling that charge, adjusting the input based on how charged the capacitor is. Switched loads, especially with EMF and similar back currents like motors have, can confuse that sampling and cause the power supply to decide that it's in a panic stage and shut off or do other things inappropriate to smooth power. If you're driving motors larger than fairly small (ie: the sorts of motors you'd scrounge out of old disk drives or CPU fans) put a diode in series with the motor, and consider a mid-sized capacitor across the motor leads. And I wouldn't suggest 'em for driving solenoid based switch motors (I think they'd *rock* for the Tortoises, though!). I have actually successfully driven a fairly large NEMA23 sized stepper motor and a Via EPIA motherboard (that booted off of CompactFlash) off of the same power supply, but there were some occasional glitches which I now think may have been power related. Of course for a hobbiest home board if your motor control PC reboots occasionally it's no big deal, for a commercial product it's a show-stopper.

Are you really drawing enough power to warrant multiple supplies? And, if so, do you have enough voltage drop to warrant spacing those supplies? If so, then maybe the problem is that you're not running thick enough power cable.