Use ATX power supply?

[DaOld Man]

Anyone thought about using the 5 VDC from an ATX computer power supply to power the Pi?

I know that PS is about 10 times bigger than the Pi, but if you have a lot of room in your project, maybe it could be used?

[Slippyblade]

That would work just fine.  Volts is volts.  You can run the Pi off a USB port, though that is a little light on amps.  I, personally, have about a dozen device charger wall warts in my bit-box though, so I've not had an issue with powering the little guy.

[DaOld Man]

Im thinking with an ATX power supply, one might be able to rig up an on/off switch, similar to the mausberry circuit switch.

[pcguysam]

If you want to get fancy:
http://www.robotshop.com/en/on-off-power-supply-switch-raspberry-pi.html?gclid=Cj0KEQjw4NmvBRCRp_yu2bzal4YBEiQAWfjpJnxDkquqCBu5AKfz4IqXD2Ks2y153_CQe6VVVopRw9EaApq78P8HAQ

Or if you don't:
http://www.amazon.com/JBtek-Raspberry-Micro-Cable-Switch/dp/B00JU24Z3W/ref=sr_1_1?ie=UTF8&qid=1442240261&sr=8-1&keywords=raspberry+pi+on+off+switch

[obcd]

So, you want to use a 60 euro or dollar supply to power a 30 euro or dollar pi.
It won't be very economical, as the supply efficency will be low when it's only used for 1% of it's expected load.
Pc motherboards check their supply voltages and activate a power_good signal that turns the supply off if those voltages are not within limits.
You will still need the micro usb connector to power the pi or you will need to power it using the gpio lines, bypassing the polyfuses.
Some power supplies need a minimum load to work properly. Your Pi just might not be enough as load.

For emulation, an old x86 pc will still give a better performance than a raspberry pi. So, if you have the room, just stick in the pc. It will have decent "audio out" (out of the box) and will connect directly to that old analog vga screen you intend to use for your arcade project. It will have 40Gig of storage space out of the box (no need to buy a 4 gig sdcard) and might come with keyboard and housing.

[Slippyblade]

If you want to get fancy:
http://www.robotshop.com/en/on-off-power-supply-switch-raspberry-pi.html?gclid=Cj0KEQjw4NmvBRCRp_yu2bzal4YBEiQAWfjpJnxDkquqCBu5AKfz4IqXD2Ks2y153_CQe6VVVopRw9EaApq78P8HAQ

Or if you don't:
http://www.amazon.com/JBtek-Raspberry-Micro-Cable-Switch/dp/B00JU24Z3W/ref=sr_1_1?ie=UTF8&qid=1442240261&sr=8-1&keywords=raspberry+pi+on+off+switch

That first one is simply an overpriced and under featured equivalent of the Mausberry.  The second one is no different that just yanking out the cord.

So, you want to use a 60 euro or dollar supply to power a 30 euro or dollar pi.

Not at all.  Where are you paying $60 for a power supply?  I've got a stack of em in my junk closet.  Or pick em up for $2 from thrift stores.

[DaOld Man]

Good comments, and I was wondering about the one that looks like it might do the same as the mausberry, but for nearly twice the price.

My thoughts for using an ATX was mainly to use an old one that most folks have laying around, just as Slippy suggested.
I was also wondering if it would help the hum on the AV output, which could be a show stopper for using a Pi in a juke box.

Of course, if necessary you could put a low ohms, high wattage resistor across the load to keep it steady (like ATX pwr supply testers do).

My main thoughts on this was to use the ATX to power up the Pi just like it does a PC motherboard.
And to get everyone thinking.
I already have a circuit in mind, I dont think it would be that hard to do.

[pcguysam]

I liked the robot shop one because of the soft reset feature.  I haven't used either one or the Mausberry.  Certainly an ATX power supply would work, and with a big empty cab the size is not an issue.

[obcd]

If something goes wrong when you use an ATX supply that can deliver 30 Amps on it's 5V rail, it will be much more spectacular than with a 2 amp supply.
Also be aware that most usb to micro usb cables are not very good at transferring power to the pi. They have very thin wires that causes a voltage drop in the cable.
A lot of USB problems with the raspberry pi where caused by a to low voltage arriving at the pi (at least that what they told people on the troubleshooting forum). It really needs 5V and not 4.7V.
The power adapters for Pi come with the wire attached to them, and only the power wires are there so that the voltage loss isn't a problem.
Obvious, if you power it using the gpio lines, this issue isn't relevant.