Card Readers: Card Types, USB Speed and Bays

Which cards it reads, and how fast it can read them

Start with the cards you own. Readers list the formats they support: SD, SDHC and SDXC, microSD, CompactFlash (Type I and II), CFast, Memory Stick and xD, and some only take microSD. Next, speed: a USB 2.0 reader moves about 30 to 40 MB/s in practice, while USB 3.x keeps up with fast cards. UHS-II cards need a UHS-II reader to exceed UHS-I speeds, so a basic reader can hold a pro card back.

External or internal: ports, bays and slot count

External readers plug into USB-A or USB-C, or a micro-USB OTG connection for phones, so match the port you have; a reader with both ends is flexible. Internal readers fit a 3.5-inch front bay and connect to a motherboard USB header, which needs a free header and a case with a spare bay. Multi-slot models list the number of slots, from one to six, and some read two cards at once. Choose the minimum that covers your cards.

Questions about Card Readers: Card Types, USB Speed and Bays

Why is my card reader slow with a fast card?

The reader, cable or port may be the limit. A USB 2.0 reader tops out far below a UHS-I card, and a UHS-II card needs a UHS-II reader on a USB 3 port. Use a direct USB 3 port, not an old hub.

Do I need a separate reader for microSD cards?

Many multi-format readers include a microSD slot, and an SD-size adapter lets a microSD card work in an SD-only reader. Some small readers are microSD only, so check the supported formats before choosing.

Can an internal card reader connect to any PC?

It needs a spare 3.5-inch bay and a free internal USB header on the motherboard, either a 9-pin USB 2.0 or a 19-pin USB 3.0 header depending on the reader, so check your case and board. Many modern cases have no such bay, in which case an external reader is simpler.