Which RAM brand is most compatible with this device?

Hi,

Your laptop has onboard DDR3 1600MHz memory.

According to the specifications for the ASUS VivoBook S300CA, it has either 2GB or 4GB of memory installed with a maximum limit of 4GB. It is mounted directly onto the motherboard and it appears as though it is not up-gradeable. So if your particular variant of the S300CA has only 2GB you cannot upgrade it to 4GB and if it has 4GB then you already have the maximum that is catered for.

Here are the Asus specifications for the S300CA series laptop https://www.asus.com/Notebooks/ASUS_Vivo...