Cheap cases will never come with PWM fans, I'm guessing it's either a 3 pin fan(meaning DC controlled) or they are power by a 4pin Molex connector.
Yeah, they're the variant with both a Molex and a 3pin connector:
View: https://www.youtube.com/watch?v=MaHtJqLjRTo
Mind you, only one end should be connected, i.e either the motherboard or the PSU. I'd advise the motherboard only.