Hello! Just in case you still need this information, I just got off a live chat with a Samsung rep since I was getting so many conflicting answers from forums, and I was amazed to hear that the Samsung S5's
write capabilities are U3, which is 250MB/s. The
read speed however is limited to Class 10 at 70MB/s.
Here's a transcript of how the conversation went down. I was actually rather amazed to see someone in a live chat actually having a solid answer and understanding what I was asking so quickly.
David: Hi, thank you for contacting Samsung Technical Support. How may I help you today?
Ratspeed: Hi David, I have what I think is a simple question, but on Google I've been trying to search for the answer, but haven't found it yet. I have the Galaxy S5, and I'm wondering what speed the external microSD memory bus is. Is it Class 10, UHS-1, or UHS-3?
David: I will be glad to assist you with the available information.
David: The S 5 device support is still class 10. Fastest speeds at up to 70MB/s read.
Ratspeed: What's the maximum write speed, do you know?
Ratspeed: Write speed?
David: It depends on the SD card.
Ratspeed: Doesn't it depend on the max speed of the bus itself though? Like isn't there a cap where it doesn't matter what speed card you have? I just want to make sure I don't spend money on a card that isn't going to be worth the money.
David: It exceeds the Speed Class (U3) spec, supporting continuous write speeds of up to 250MB/s.
Ratspeed: Really...
David: Yes.
Ratspeed: So, say for instance, if I were to get the U3 ExtremePro from SanDisk, which says it does 90 write speed, it'll be able to handle that? I'm going to be doing video (the thing has a great camera) so that's what I've been specifically concerned about is the write speed so the video doesn't lag.
David: Yes.
So I hope this info helps someone have a better time trying to find the answer than I did.
Ratspeed: Awesome
Wow... 250MB/s. Alright, thank you!
David: You're welcome.