I have a Mac mini Mid 2011 2.3 GHz Intel Core i5. I received as a gift an 8GB memory kit. The memory spec for my Mac says it needs PC3-10600 DDR3. The kit I have is PC3-8500 DDR3. In particular, the kit is Crucial part number CT2CP51264BC1067.

Will the memory I have work in my Mac?

1 Answer 1


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.

  • Does that hold true in the other direction? Can I put faster ram in a slower computer?
    – Michael H.
    Jan 31, 2012 at 16:59
  • Yep, as long as the modules are the same type physically and electrically. In this case there's actually no bandwidth drop from the computer's perspective. The RAM module is just running at a fraction of the max speed it was designed for.
    – Vickash
    Feb 1, 2012 at 22:50
  • Sweet, thanks. Means I can offer up the memory I took out of my 2011 MBP to friends with 2010 models...
    – Michael H.
    Feb 2, 2012 at 17:07

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