First off, the SD card doesn't provide any additional operational memory, and makes no difference in overall player performance. It only serves a single purpose, which is to enlarge the storage space for installed channels. If you fill the memory with channels, the player will offload the lesser used channels to make room for a new one. If you want to play the offloaded channel, it will take a short time (maybe 10 seconds or so) to load the channel back on and offload another little used channel.
As to card size, it's unlikely that any more than 2 GB would ever be used. I would say a 4 GB card is more than enough for almost any user. Anything larger is just wasted.
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Thank you for your response. I did not see this until I got home. I did put a larger card in it. And you are right after it reformatted the card then it updated channels and movies. Probably because I used up space in the unit. Thank you for giving me a answer to my question. I like it so far. We are going to get a faster internet by the coming Tuesday. Our tv is a 10 year old SamSung 55” 7000 series with 240 meg hurtz it was the high end when we bought it. So we just decide just update with a streaming devise. Even with our slow internet late last night things would load ok. But today with the wife working from home we need more speed. Thanks again!!
I'm using 16 GB cards, exceeded 4 GB usage almost immediately on one, so I definitely wouldn't bother with a 4 GB. If you plug in a lot of different USB drives, it'll store info on the card when the drive is scanned so the next time it recognizes the drive, it doesn't have to re-scan. I haven't used the USB port much, but it's another way the memory can get used up.
Seems to me I picked up 16 GB cards for the same price as Roku's 2 GB cards, and they're faster than necessary. Happened to be on sale when I walked in the store. (Probably the last time I walked into any store, for that matter).