Any PC PSU from the last ten years will have plenty of amps on the 12V rail. I wired one up from a PC PSU that I would have otherwise thrown away. If you're trying to power multiple chargers you may need a PSU from the last 5 years that has multiple 20A+ 12V rails. I have a relatively cheap one in my PC right now and it looks like it has three 12V rails that are above 30A each. That would run a half a dozen decent chargers with room to spare.