4GB Total. One 4GB PC3-8500 204 pin SODIMM DDR3 1066MHz Genuine CMS brand, CMS is one of the most trusted names in the Computer Memory industry and this product carries a Lifetime Warranty from CMS COMPATIBLE WITH: Apple Mac mini "Core 2 Duo" 2.0 (Early 2009) Specs Identifiers: Early 2009/NVIDIA - MB463LL/A* - Macmini3,1 - A1283 - 2264 By default, 1 GB is installed as a single module (MB463LL/A) and 2 GB is installed as two 1 GB modules (MB464LL/A). Officially, this model is capable of supporting 4 GB of RAM, but as first reported by MacminiColo, this model unofficially can use 8 GB of RAM after applying EFI Firmware Update 1.2