http://support.lenovo.com/en_US/detail.page?LegacyDocID=MIGR-71785

PC3-8500 Non-Parity (NP) Double Data Rate Three (DDR3) Technology
Two SO-DIMM Slots
The use of 1067 MHz SO DIMM memory is recommended for this system.
256 MB, 512 MB, 1 GB, 2GB, or 4GB memory
Supports up to 8GB maximum memory

je to limitovane chipsetom ktory podporuje maximalnu velkost jedneho modulu, ja mam napr o nieco starsi book hp a maximalne podporuje 2 GB moduly. (takze tam dam max 4 giga ram)

takze kup 2 4GB moduly bude to fachcit pohode. staci aby mali rovnake frekvencie (podla toho sheetu iba 1066)