It doesn't matter, the board only draws as much power as it needs.
Anyway, personally, I wouldn't trust anything without adjustable power rails. If I wanted a new PSU for a Model 3, I would pick up a Mean Well QP-150-3A. Adjustable +3.3V and +5V rails that are both 15A max (plenty enough for Model 3).
For Model 2 that only uses +5V, be careful with these PC power supplies. I was recently called to fix a Virtua Fighter 2 on site. It had a faulty coin mech. When I got there I noticed the picture was strobing, so I peeked inside the cab and saw that it had a computer PSU rigged inside. I measured the voltage at the filter board connectors, it was showing 5.4V. The operator was next to me and I was like, you'll kill this game with this voltage. Even though the cab had been running fine for months (apart from the strobing which he didn't mind...), I had him convinced that it still needs to be fixed. The next day I fixed the shitty wiring job (screw terminals, hot glue and electrical tape; love it) and replaced the power supply with a regular 5V / 12V arcade PSU. Voltages were spot on and strobing was gone.
I don't know why it wasn't regulating the +5V line. Maybe the +3.3V rail being unloaded played into it.