@John_Ridley they don’t work like a 7805 linear regulator, where the extra voltage is just “burned off” (well, the Linistep does), but more like a switching power supply (to be exact, a step-down regulator), using the motor’s coil as the inductor. In theory, a higher voltage shouldn’t make the drivers run hotter.
@Thomas_Sanladerer commercial CNC machines drive 5v steppers from 50v and higher sometimes. The higher the voltage, the faster the coils can charge due to their inductive nature (as it was explained to me) which results in faster achievable speeds. I guess this is more needed on those machines due to the high down-gear that they have to deal with on lead-screws. But I’ve run into that limitation myself on the Z axis (not being able to move as fast as I’d like)
@ThantiK that is true indeed and a real issue on the bipolar motor we’re using. It affects only high step rates, though, which would yield well over 500mm/s on a typical RepRap. With my current setup i have no problem of achieving 250mm/s, 8000mm/s² at a jerk of 20mm/s (on X, throwing the extruder around), which i deem acceptable for a printer. I value acceleration more than top speed, since most travel moves are short and when printing hex infill, a higher acceleration value has a much higher influence on overall speed than a higher top speed.
Details:
Pololu 4983 drivers, 42BYGH0425 steppers, 12 tooth HTD-3M pulleys. 12V.
I’d recommend buying a supply that uses a giant 12V rail, and powers the 5V and 3.3V with DC-DC converters off the 12V. That way you won’t have to mess with load resistors and shit like that.
And yeah, you’ll pay a couple tens more than for a cheapie, but you do get a supply that will provide you with 500 or 600 watts of 12V without blinking, typically.
(That is, if you want to go with ATX)
+jasper janssen How can I tell if a supply is configured that way? Can you recommend a specific model.
For the record, in case anyone is paying attention, I wound up ordering one of the 12V 30A bricks from Amazon. It arrived saturday. I wired it up and it seems OK at first glance. It has a variable speed fan which is very quiet at idle, but as soon as I hit it with a load the fan spins up and gets noisy. One thing I miss is having a power switch, however. That was my Emergency Stop before.
An enclosed power brick that plugs directly into the wall, or the one with screw terminals? If the latter, you should wire it through an entry module (basically just a little screw-mountable box which you plug a power cable into) and a fuse. Most power entry modules also have switches built in.
The one with screw terminals. One of those entry modules would make it nice for eventually mounting all the electronics in a single enclosure.
Heh, then you should definitely get a power entry+fuse module. Your old ATX PSU probably had one built in. The amazon ones don’t. Without the fuse, you risk burning down your desk inadvertently when a wire gets crossed/melts on your controller. As opposed to deliberately, via your extruder tip, which is normal. 
Plus you can get your emergency stop switch back, too.