There's an important difference between memory (often called RAM) and storage.
Memory/RAM is where a computer does it's work, and it's cleared when the power is turned off or the computer is rebooted.
Storage is more persistent; anything which needs to be kept is saved to some form of storage.
For example, if you're editing a file (e.g. a shopping list or a Python script) then that's saved in storage; it's still there when you reboot your computer. However, the editor (or even the Python script you were editing) runs in memory; unless you save your work to storage it's gone when you reboot your computer.
The memory in a Raspberry Pi is fixed; unlike a typical desktop or laptop PC it's not possible to add more. Fortunately, this is not a problem for you because the;
RAM in a Raspberry Pi is ample for most people's purposes and most of the OSes which people run on it.
SD cards you ask about are used for storage.
I'm not sure what the maximum capacity of SD card supported by Raspberry Pi is, but Adding storage to your Raspberry Pi indicates that 128GB (four times the 32GB you ask about!) is fine... and lists some other options, including USB flash drives and HDDs (Hard Disc Drives) like WD's 314GB PiDrive.
Hello this is my first post. I just received a 3B and was wondering the same thing. I have a Samsung 64 gb class 10 card in one of my phones so formatted it to Fat32 using guiformat 32 from http://www.ridgecrop.demon.co.uk/guiformat.exe
It worked perfectly. I wanted to run retropie with a load of roms and was able to format the card as needed then download the image for retropie then use 7zip to unarchive then win32 disk imager to write the image to the card. I hope this answers your question. on another note if you are looking for a power supply for the pie with an on off switch they can be had on Amazon.ca
