I'm going to upgrade my Fujitsu Lifebook A512 (Intel Core i3) RAM:

  • Original: 4GB 2Rx8 PC3L-12800S-11-12-F3 | Works fine
  • New: 4GB 1Rx8 PC3L-12800S-11-13-B4 | With this RAM (alone or with the original) the computer doesn't start, with all the lights turned on except HDD, Num & caps lock


Basically the new RAM should be compatible with the motherboard (DDR3, 1600MHz, Non-ECC, 1.5V, Unbuffered, SODIMM, 204-pin...). Where is the mistake? 13-B4 instead of 12-F3 or the new RAM is broken?


I'm making an assumption here, correct me if I'm wrong as I cant comment. I believe your adding a second ram stick, instead of replacing the one you have.

The key here is the 1Rx8 and 2Rx8. 1Rx8 = memory on one side of the RAM 2Rx8 = memory on both sides.

Based on other superuser & tomshardware answers, these should be compatible, but not always. Its recommended to get ram in kits.

It may be worthwhile trying another 1Rx8 chip along side the one you already have.

  • Thanks, but I bought another RAM from Kingstorn. This new one works fine. – SquareBoot Aug 2 '16 at 11:53

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