Testing a Macbook 16 inch that I bought Refurbished. It's an i9 2.4. While running it alongside a i9 2.3 using Geekbench on each, I heard what I can only describe as "cracking" noises coming from the chasis. It definitely is not that cracking speaker issue, but I assume could have something to do with things heating up. I suppose I'm willing to live with this but I have not encountered it on any of the other 16 inches that I've tested out. Makes me wonder if this is why it was returned/refurbished. Assume with something like this it's not wise to keep the model. It will be my 3rd return this month: the first had a bad battery, second had a dim screen (apple store agreed that I should return both), and now this.