fast, but for whom? — Compatibility issues and thermals have, so far, kept SD Express from taking off. Enlarge / Samsung's SD Express-compatible microSD cards.Samsung Big news for people who like (physically) small storage: Samsung says that it is sampling its first microSD cards that support the SD Express standard, which will allow them to hit sustained read speeds of as much as 800MB per second. That's a pretty substantial boost over current SD cards, which tend to top out around 80MB or ...