What do you do when you have a four-pin fan? I have a MacBook Pro, and the fans just got replaced on it, but they're still good (just noisy) and I want to wire them up for my terrarium. A link to a picture from Amazon is below. I've wired case fans before, but all these wires are identical and I dont know which to hook up. I'm fairly hesitant to do trial-and-error, out of fear of electrocution or shorting a circuit or something.
Thank you for any input!