Looking for 1066 MHz PC3-8500 DDR3 SDRAM any reason to avoid 1600MHz?

I’m trying to help somebody looking to upgrade the Ram in a 2010 MacBook Pro.

Officially it’s supposed to take 1066 MHz PC3-8500 DDR3 SDRAM, but it’s actually hard to find RAM that slow in 2021. 1600MHz is the speed I’m finding. Should I go out of my way to find the 1066MHz speed Ram, or will the 1600 be fine?

OWC sells 1066:


I would go with their recommendation, unless Crucial or some other name brand says 1600 is a workable upgrade (i.e. they sell 1600 for the 2010 MBP).

Normally you’ll have no issues installing faster RAM in a slot if the only difference is clock speed, and you might even get a small speed boost if the system unofficially supports faster RAM (IIRC, your laptop unofficially can run 1333.)

Here’s a thread where you can see people having issues doing this, though, and the reason is the differing voltage in the newer sticks, not the clock speed. So while 1600 would likely be fine, you still probably want to stick with OWC-recommended memory as John said.