Soon you will be able to purchase new SD cards with the SD Version 7.0 specification. The new specification supports up to 985MB/s of throughput, which comes courtesy of PCIe and NVMe interfaces, and up to 128TB of capacity. That's quite the jump over the current 2TB limit.
985MB/s of throughput for a simple SD card may seem ludicrous, but higher-resolution video, VR, automotive use-cases, and IoT applications are steadily encroaching upon the performance limits of today's products.
OEMs are notoriously slow to adopt radically new designs, so the new SD Express specification is also backward compatible with the legacy UHS-I interface. Backward compatibility means we will see end devices come to market faster, whereas other faster interfaces have withered on the vine due to reworked interfaces that prevent broad uptake.
The specification has reserved space for new pins for future use, so it also provides room for forward progress (PDF). The specification also accommodates up to 1.8W of power consumption, which will help boost performance. The NVMe 1.3 protocol also brings several new features to SD cards, like Host Memory Buffer (HMB), which sets aside a small portion of system memory to boost performance, and Multi-Queue support, which improves performance during simultaneous file transfers.
The SD association will bring the interface to SDHX, SDXC, and SDUC cards first, but it also plans to bring the speedy connection to MicroSD cards in the future. The first cards wielding the improved interface should come to market in 2019.
