128GB (4x32GB) DDR3 ECC PC3-10600 1333MHz SDRAM for Mac Pro 2013 Model ID# MacPro6,1. OWC Memory for Mac Pros fully meets Apple"s specifications w/ special attention to proper thermal specifications. Special 32GB module use information: Due to processor design and memory architectures, 32GB module utilization occurs at a bus speed of 1066MHz with Apple Mac Pro 2013 E5-16XXv2 4-Core, 6-Core, and 8-Core processor equipped models, 800MHz with factory 12-Core or after-market E5-26XX equipped models.