Put memory from a 2.7GHz Mac Mini into a 2.4 GHz MacBook

You can find the specifications for your computer here.

Specifically, the unit has the following (with a maximum RAM capacity of 8GB):

• RAM Type: PC3-8500 DDR3 SO-DIMMs
• Min. RAM Speed: 1066 MHz

So buying RAM that meets those specs is sufficient. As for buying "Apple" branded memory, it doesn't seem necessary. I always look to Mushkin, which sells "Apple" tested memory and have relied on them exclusively, but I have read others running Macs with Kingston, Crucial, or any one of the many other brands available without reporting issues.

Match the type and speed, and you shouldn't have any problem. Newegg has a 4GB package (2x2GB sticks) and a 8GB package (2x4GB sticks) for relatively cheap. They should give you an idea of what kind of prices to expect. Searching google yields quite a few results if you are interested in other brands or other configurations.

Lastly, consult iFixit for details on how to upgrade the memory for your specific model.

PC3-10600 RAM runs at a clock speed of 1333Mhz. The older PC3-8500 runs at a speed of 1066Mhz. As long as there aren't any other physical or voltage requirement differences between the two types of memory (and there shouldn't be in your case, since both are DDR3 SO-DIMMS), your system should accept it.

Keep in mind that the system's memory bus will automatically adjust to suit the rated speed of the slowest memory module installed into it. So rather than running the memory at 1333Mhz, it will drop down to 1066Mhz and you'll lose some memory bandwidth.

If you want, you can look at this Wikipedia entry to start figuring out exactly how much. As for real world performance, it really depends on what you're doing. Increasing the amount of memory available while losing some bandwidth might be a good idea if you leave everything open all the time.

But if you have specific applications that require a high amount of memory I/O, like a big database for example, speed might be more important. For the average Mac user though, I'd say sheer volume would be preferential.