Delock SD Express Card Reader

Introduction

Delock is a German company offering a variety of IT hardware. Their foray into SD Express includes both cards and card readers. The SD Express reader 91006 supports SD Express (SD7.1) cards as well as UHS-II and UHS-I cards, more on compatibility later.

The reader supports USB 3.2 Gen 2 and has a USB Type-C connector (USB-C). Delock provides a six month warranty. The reader tested is model 91006 with EAN 4043619910069. The reader is made in Taiwan.

The reader case is made from aluminum. A card access light is located the back of the reader. The bottom of the reader is covered with a non-slip surface.

The card reader measures 1.8 x 1.6 x 0.35 inches (45 x 41 x 9mm) not including the USB cable section. The reader includes a one foot (30cm) USB cable.

Inside the reader the Realtek RTL9211 controller handles the USB3.2 Gen2 to PCIe interface and is able to communicate directly with SD Express cards. On the opposite side of the board the Realtek RTS5261 resides, which is able to handle the fallback SDR104 interface for legacy UHS-II and UHS-I cards.

Performance

The Delock SD Express Card Reader was tested using SD Express, UHS-II and UHS-I SD cards. As expected, the highest benchmarks were seen with SD Express cards. The 811.9 MB/s sequential read and 498.7 MB/s sequential write were impressive.

Unfortunately in this reader UHS-II cards are limited to UHS-I mode. Performance of UHS-II and UHS-I cards in the reader reached sequential benchmarks of 55.0 MB/s read and 48.8 MB/s write, which are much lower than expected from the 104MB/s potential offered by SDR104.

There is a problem trying to bridge new and existing technology. Curiously, SD Association's definition states, "SD Express will not support UHS-II interface." This may be due to SD Express cards using the same pins and connectors as existing SD UHS-II cards. SD Express does include support UHS-I interface using the legacy pins (thereby allowing compatibility with numerous existing devices). It may be possible for a card to support both UHS-II and SD Express modes, but the current card controllers from Phison and Silicon Motion do not. Not being able to use SD Express cards at UHS-II speed could be a problem. From a card reader and device perspective, it should be possible to handle both UHS-II and SD Express in the same device. Genesys Logic released specifications for a card reader controller (GL9767) that supports both SD Express (SD 7.1) and UHS-II (SD 4.0), although the current Realtek and JMicron card reader controller solutions do not, as seen in this Delock reader. There is still hope that devices may be compatible with both standards, allowing a smoother transition to the benefits of SD Express without sacrificing UHS-II compatibility.

Reader: Delock SD Express Card Reader
Benchmark: CrystalDiskMark 8.0.4 x64
Program settings: 1000 MB, 5 passes, random test data
Operating system: Windows 11 Pro
Motherboard: Gigabyte Z690 UD AX DDR4
Processor: Intel Core i5 @ 3.30GHz
RAM: 32GB DDR4 3200

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