I am attempting to upgrade the RAM on my sister's Dell Optiplex 780. According to my research, the board should support 16GB. Presently, it has 4GB in the form 4 1GB sticks. I purchased 2 4GB sticks to replace 2 of the current 1GB sticks. They are "Micron 4GB 1Rx8 240pin DDR3-1600MHz PC3 12800U MT8JTF51264AZ-1G6E1 DIMM". From my research, they are compatible with the system.
When I tried installing the new RAM, the system would not boot (only beep/buzz obnoxiously). I upgraded the BIOS to A15 hoping this would help, but it did not. The computer still will not boot with the new RAM. The "1" and "3" diagnostic lights turn on which, to quote the Dell manual, means "