Crucial and OWC both say that the 17" MacBook Pro (early 2011) supports 16 GB. But both only offer 1333 MHz when I select to buy.

Rightnow I've got a single 8GB 1600 MHz chip, have had it for years and it works fine.

Would this model have issues with two 8GB 1600 MHz chips?

  • RAM can run slower than its spec'd speed - it just means it can run UP TO that speed. So it's really only a price issue. It's likely what you have in there right now is just running at 1333.
    – xaxxon
    Commented Sep 10, 2016 at 10:39
  • "single 8GB 1600 MHz chip' - is this installed in this MBP and has been running ok? If I understand you correctly, you're asking if an additional 1600 MHz chip of equivalent specs can be added, increasing RAM to 16GB, yes?
    – IconDaemon
    Commented Sep 10, 2016 at 10:57
  • why do you want 16GB's of ram exactly?
    – OzzieSpin
    Commented Sep 10, 2016 at 15:18
  • Here is OWC's web page offering the memory you want. Crucial seems to be out of stock. You can buy Crucial at Micro Center. While OWC says their memory will work in your Mac, Crucial says their memory will not. Commented Sep 10, 2016 at 18:16

1 Answer 1


Your MacBook Pro has two memory slots designed to take 204-pin PC-10600 (1333 MHz) DDR3 SO-DIMM memory chips.

Apple's official position is that this model supports up to 8GB of memory, but real world tests have proven the machine to work fine with 16GB, so both Crucial and OWC are correct in what they say.

If both of them sell the 1333MHz chips, assuming they are 204-pin PC-10600 (1333 MHz) DDR3 SO-DIMM memory chips, then these will work as they are the correct specs for your machine. Xaxxon's comment about the likely speed of what your 1600MHz chip is running at is correct. Paying for 1600MHz chips are just a waste of money.

If it was me I would go ahead and purchase two of them and install them into your computer to get the 16GB you want.

You could try just purchasing one and adding it to your machine, but you may be risking inconsistent/random performance issues having one 1600MHz chip and one 1333MHz chip installed simultaneously.

Of course, it's up to you and you could just test this and see how you go. But, if it's cheaper to purchase the two at the same time as opposed to buying one and then another later, I'd just buy the two new 1333MHz chips. Having two identical chips is the safest option.

  • In theory, a 1600MHz chip should work just fine in a 1333MHz slot, but in practice sometimes the computer tries to run the faster chip at the faster speed and it just doens't work. Generally, if two different speed chips are in each slot, the system successfully uses the slower speed for both of them, so a 1600+1333 combination might work when a 1600+1600 combination does not. When I want to be confident things will work, I just order whatever OWC sells. When I am feeling cheap I use OWC's specs and find the cheapest price available.
    – j-beda
    Commented Sep 10, 2016 at 16:50
  • @j-beda Agreed. OWC would be my preference too.
    – Monomeeth
    Commented Sep 10, 2016 at 21:15
  • Apple said: 8GB and 1333. About his Mac says: "16GB" and "Your Mac contains 2 memory slots, each of which accepts a 1600 MHz DDR3 memory module." If these info can be trusted, it not only accepts 1600 but runs them at 1600. Commented Mar 13, 2018 at 1:22

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .