Some of those power supplies are low amps per 12v rail. I think it is more on the 5v side for some reason. Even if it says 700w it doesn’t mean on the 12v rail.
I could be wrong but I burned out 2 of them so far, that is why I switched to the style I ship with the kits.
That’s the best I could come up with when I fried the second one. Something about them does not work well with the heated beds for sure.