Nekompatibilní RAM. Rada je jednoduchá - použít jinou paměť.
http://www.fixya.com/support/t2271808-problem_upgr ading_acer_extensa_5620z
http://www.techsupportforum.com/forums/f15/upgrade -acer-extensa-5620z-548455.html
The HyperX-RAM does not work in Dual-Channel-Mode on the 5620z!!! One 2GB-DIMM alone is fine, but with two DIMMs Windows will not boot and show a blue screen that says, that the PFN-List was corrupt.