Sorgelig wrote: Even very new UHS-3 cards with additional pins still can be used in generic SD readers with reduced speed as far as i know.
Yes, even UHS-3 cards will work but with hard limit on performance (since there are no extra pins line and 4 bit SD 3.0 interface working on 50MHz is used. Didn't make any formal performance measurements but if max burst transfer rate is 200Mbit/s then we cannot get more than ~20MBytes/s in reality.
I've never measured 104MHz clock frequency on SD so assuming that it always works on 50MHz.
See more: https://www.sdcard.org/developers/overv ... index.html