The laptop only has 2 SODIMM slots so they are putting a 4GB and a 2GB. To upgrade to 8GB, you are going to have to take out the 2GB and buy a 4GB SODIMM. I would, personally, just spend the extra $15 or so to buy 8GB (2x4) of the same brand just to be safe. But a 4GB will work but make sure that it is DDR3-1333 (PC3-10600). Hope this helps.