And don't forget that a lot of PC power supplies don't have -5, so if you need that - oh well...
Sorry for the bump to this thread, but I ran across it will looking for something.
I was working on working on some boards that I've had piled up here and was working on my Vanguard boards. The game requires -5V on the speech board and my ATX supply doesn't (didn't) have -5V coming out of it. I thought that was a little weird and out of curiosity took the PSU apart. On the PCB all parts and voltages were silk screened on the PCB and after looking a little, I found a "-5V" marker and started looking around it and saw it was missing a capacitor in the area as well. I tested on the other end of where the cap would be and there was -4.93V... so it was there. Just put in a capacitor for filter (I went with the same value as the 5V line which was 1000uf 10V) and ran a wire out of the thing and called it done.
I have no idea why they didn't just populate the -5V rail and run the wire as the ATX connector has a spot for -5V... but whatever.
Point of the story is if you have an ATX supply that doesn't have -5V out of it it might be worth opening the thing up and making sure they didn't decide to save half a cent at the factory by leaving that section unpopulated.
FWIW, I consider the ATX power supplies to be great for arcade boards... they're made to be safe. If there's a short or anything like that they shut down cleanly. They're made to do that because the boards they're made to be hooked up to are a liiiiiiiittle more finicky and fragile than a Street Fighter machine. Plus, having one in a cabinet is nice because it circulates air, even if just a little, which is nice.
If I had the money, I'd put them in every one of my machines that has an arcade style switcher in it.
Sidenote: The Vanguard boards actually worked, with sound and speech... so, that was really a nice surprise since they were given to me in a big pile of "junk" boards.