Memory speeds can be confusing, especially when upgrading. You may look at your “About This Mac” info and see that your iMac uses 1867MHz DDR3 modules. But when you start shopping around, you find some manufacturers are selling memory labeled 1867MHz, while others are marketing 1866MHz. So, is there a difference? Is one faster than the other?
No. The reality is that they are the same.
Some computer makers, such as Apple, round the full spec (1866.6MHz) to 1867MHz and thus these listings. While this is the case with the frequency speed, other programmable parameters do create differences, and OWC memory is explicitly certified to meet, if not exceed, the stringent specifications Apple expects. This ensures complete compatibility with Apple computers, as well as exceptional performance and compatibility with PC systems. Memory that can work in a PC does not always provide optimal results in a Mac, but due to Apple’s requirements for Macs, memory that meets its specifications will always satisfy PC requirements.
I am not sure why Apple does this rounding on the speeds of SO-DIMM memory but does not do it on their DIMM utilizing systems like the Mac Pro 2013 or the Mac Pro 2019, where they list 1866MHz and 2666MHz speeds respectively. I would suspect it is different hardware marketing leads that have independently chosen the two paths. I would further speculate this is because the DIMM modules used are server spec ECC type DIMMs, which are more consistent in Apple spec compliance, vs. SO-DIMMs that are a consumer-level memory and more subject to spec issues. By calling it 1867MHz, it helps ensure customers upgrade using trusted memory manufacturers like OWC, who are sure to provide the correct specification memory for optimal Mac operation.
So, whether you choose to round up or truncate a decimal place, 1866MHz and 1867MHz DDR3 memory are the same speed, just as 2666MHz and 2667MHz DDR4 are the same. And no matter how Apple chooses to label its RAM, you can rest assured that OWC follows suit—ensuring your confidence when buying the highest quality memory available with a savings of up to 77% compared to Apple.
– OWC Larry