Summary: This works perfect with ASUS s400ca. From the very moment after I click this memory chip into my laptop, I can feel the difference in speed. Mine had 4gb and now 8gb. With 4bg only, my laptop did not have enough free memory so had to read and write on the hard drive. Now, my laptop displays a webpage at the moment it downloads one due to a plenty of free memory. For ASUS s400ca, buying 8gbs is unnecessary. Buy this product. You wouldn't regret.
Summary: I didn't get to use this item much because of my laptops faulty motherboard, it was very fast and my computer booted up very quickly. I bought this because I thought the RAM was the problem of it not charging, I also bought a NEW AC adapter. Afterall I ended up buying a new computer.