32GB (2 x 16GB) DDR3 1866MHz PC3-14900 ECC RDIMM for Apple Mac Pro 6, 1 Late 2013 6-Core Intel Xeon E5 3.5GH z ME253LL/A CTO. This ECC RDIMM ( Registered memory) is the fastest rated DDR3 memory upgrade available for the Apple Mac Pro 2013. Although Apple Supports only 64GB, NEMIX RAM memory upgrades for Apple Mac Pro Late 2013 6, 1 are supported up to 128GB using RDIMMs. If using ECC UDIMM max supported memory is 64GB. Do not mix ECC UDIMM and Registered (RDIMM) memory modules. Please contact us for sales, volume discounts or installation support.