We have passed compatibility testing on SD cards and USB drives up to 32GB.
However, bear in mind that if there are thousands of files on your card and they are in different folders or formats (i.e. MP3, .avi, .txt etc.,) this will probably slow the frame's processor.
If your card contains thousands of pictures, the frame's processor, much like a PC, will require more time to process such large data content, so the overall speed of the frame might not be as quick as if you had, say, 100's of pictures.
Due to technology limitations at the present time, NIX Digital Frames will not accept external hard drives or being connected via a USB hub.