Mac Pro users demand the highest performance from their systems, especially when working with digital media applications. Corsair's Mac Memory is specifically designed for rock-solid stability in demanding digital media rich environments. Corsair Mac Memory allows users to maximize memory capacity & throughput to increase their systems performance. Mac Memory modules are Fully-Buffered DIMMs, or FB-DIMMs, which are different than the typical memory running in standard PCs. In an FB-DIMM module, the memory controller does not write directly to the memory module, but to a buffer, which then writes to the module. This buffer, the Advanced Memory Buffer (AMB) can also provide built-in error checking & correction. Built to Corsair's legendary quality & reliability standards, Mac Memory FB-DIMM modules are fully tested to ensure maximum compatibility & performance in Apple Mac Pro products. Adding system memory is one of the most effective ways to improve overall performance & Corsair's Mac Memory offers a full line of choices for upgrading your specific Mac Pro platform. FB-DIMMs require two identical modules to be installed at once for proper operation. Corsair's Mac memory kits are tested at Apple Developer Compatibility Labs & work with most Mac Book Pro, i Mac, & Mac mini systems shipped in 2011. Crucial Known Compatibility list for CMSA8GX3M1A1333C9 17" Mac Book Pro Intel Core i 7 MC725 2.2 G Hz QC Core i 7 (Early 2011) 15" Mac Book Pro Intel Core i 7 MC723 2.2 G Hz QC Core i 7 (Early 2011) 15" Mac Book Pro Intel Core i 7 MC721 2.0 G Hz QC Core i 7 (Early 2011) 13" Mac Book Pro Intel Core i 7 MC724 2.7 G Hz DC Core i 7 (Early 2011) 13" Mac Book Pro Intel Core i 5 MC700 2.3 G Hz DC Core i 5 (Early 2011) 17" Mac Book Pro Intel Core i 7 MD311 2.4 G Hz QC Core i 7 (Late 2011) 15" Mac Book Pro Intel Core i 7 MD318 2.2 G Hz QC Core i 7 (Late 2011) 15" Mac Book Pro Intel Core i 7 MD322 2.4 G Hz QC Core i 7 (Late 2011) 13" Mac Book Pro Intel Core i 5 MD313 2.4 G Hz DC Core i 5 (Late 2011) 13" Mac Book Pro Intel Core i 7 MD314 2.8 G Hz DC Core i 7 (Late 2011) 27" i Mac Intel Core i 5 MC814 3.1 G Hz QC Core i 5 (Mid 2011) 27" i Mac Intel Core i 5 MC813 2.7 G Hz QC Core i 5 (Mid 2011) 21.5" i Mac Intel Core i 5 MC812 2.7 G Hz QC Core i 5 (Mid 2011) 21.5" i Mac Intel Core i 5 MC309 2.5 G Hz QC Core i 5 (Mid 2011) Mac Mini Server Core i 7 MC815 2.0 G Hz QC Core i 7 (Mid 2011) Mac Mini Core i 5 MC816 2.3 G Hz DC Core i 5 (Mid 2011) Mac Mini Core i 5 MC936 2.5 G Hz DC Core i 5 (Mid 2011)