Memory Upgrade on Macbook 13" Mid 2010

Question

Hi,
Reviewed the forums regarding upgrading from 4GB to 8GB on a Macbook 13" (mid-2010). It appears many have had success with QWC.  I just wanted to run this by folks to get any feedback.
I was at BestBuy this evening and picked up some PNY memory (2 x 4GB). The Bestbuy clerk is also an Apple user.  Yet, the Apple guy at BestBuy, with the black shirt on, said "only about 70% of the time does the PNY memory work).
What I thought interesting is the PNY is for 1066 MHz @ DDR3.  When I run my Serial # on the Apple check site, it says my Macbook is 1066 MHz, yet, when I click on the Apple icon, strike About this Mac, the memory is 4 GB 1067 MHz.  Any idea why the descrepency from the serial # site of 1066 MHz and my Macbook telling me 1067 MHz.  Is this why the PNY won't work (which it didn't)?
Thanks,

Answer 1

If you bought your RAM at a place that also sells PC RAM you may have gotten mislabelled RAM. PCs can handle different RAM speeds so they’ll often label higher speed RAM as a lower speed rather than make two different speeds of RAM. But Macs are much more picky. They require a RAM stick to be exactly 667mhz not 675mhz or 800mhz. The way to tell is to put one of your old RAM sticks in and it will force the new RAM to run at the correct speed.
This is from one review of PNY RAM:
"These modules are actually 800Mhz. PNY no longer makes or sells 667Mhz modules. Not all computers that require 667Mhz are compatible with 2 800Mhz modules. They refuse to down clock properly. This is especially true with a number of Core 2 Duo MacBooks. Spoke to PNY support, they flat out told me that yes, they sell 800Mhz modules in 667Mhz packaging. If you RMA a module that is 667Mhz (or supposed to be 667Mhz) they will replace it with an 800Mhz module as they no longer have any 667Mhz SODIMMs, not even for RMA replacement!"