According to the specs of my Fujitsu Esprimo P2560 desktop the maximum RAM is 8 GB. There are 2 slots and currently there are 2+2 GB installed. I tried to upgrade the memory bank by removing one of the 2GB and replace it with a 4 GB module but this did not work. The module in question is a 4 GB 240-pin DDR3 8500 1066 MHz. Exactly the same as the 2 GB. Furthermore, I have the latest BIOS installed. Anyone out there have a clue?