RAM memory puzzle

Hi, I'm going to have a go at installing memory into the 2 empty slots on my late 09 27" desktop. My Mac says it has 4 gig of 1067 MHz DDR3 but when I following the installation instruction from the About This Mac pop up and scroll down to my computer is says it takes 1066 MHz DDR3 - that's th tony difference - 1066 or 1067. When I look on amazon the the 1067 (that is supposedly already installed) the MFGR doesn't list my computer as compatible with the 1067. SO I'm totally confused.

Go here, http://www.crucial.com/usa/en/memory?cm_re=homepage-_-main-body-_-us-buy-memory-button, go through their "Upgrade Wizard" and see what it lists as memory for your Mac, then see if you can find it listed on ebay or amazon, for less money.

According to Mactracker your Late 2009 27" iMac takes:

Maximum Memory 32 GB (Core i5 or Core i7 Actual) 16 GB (Apple)
Memory Slots 4 - 204-pin PC3-8500 (1066 MHz) DDR3 SO-DIMM

1066 MHz is a "clock speed." I'm quite certain that 1067 is the same, just different rounding - up vs down.

As gsahli mentioned it's a rounding "thing". I believe the actual RAM speed is 1066.66MHz. Thus 1066MHz is not "technically" as accurate as saying 1067MHz (if rounding to 4 digits). But at the end of the day...it's the same thing inside the computer.

- Nick