Even the fastest SD cards are still quite slow. This poses a great challenge for 8K video recording, handheld PC gaming, and other technologies that continually demand greater data transfer speeds and improved storage reliability. So, to remediate the problem, the SD Association has announced its new SD 9.1 specification, which achieves a data transfer rate two times greater than any existing SD card.
Previously, high-end SD cards utilized PCIe Gen3 connectivity and were limited to speeds of 985 MBps or less. The new SD 9.1 spec introduces PCIe Gen4 connectivity and hits a maximum card speed of 1.9 GBps—plenty of bandwidth for 8K video files, video games, or other bloated media. Of course, you don’t need to be a videographer or a big-time nerd to see the benefits of SD 9.1. Even a modest file transfer will feel noticeably quicker over a PCIe Gen4 connection.
But with increased speed comes increased heat. And when SD cards get too hot, they must be throttled—transfer speed is temporarily reduced to cool things off. This keeps the card safe but can ruin an active recording or file transfer. To avoid throttling and maintain continuous speeds, the SD 9.1 spec contains new power management thresholds and thermal performance upgrades, including the ability for a host device (camera, game console, etc) to control an SD card’s internal temperature.
Interestingly, SD 9.1 also boosts the reliability of multi-stream recording. The details are a bit confusing, but the gist is as follows: SD 9.1 can more efficiently manage simultaneous recording from multiple cameras or other sources. Check out the SD 9.1 white paper if you need additional details on this particular subject.
Along with the introduction of SD 9.1, the SD Association is rolling out four new speed classes for existing SD Express card formats. These speed classes (SD Express Speed Class 150, Speed Class 300, Speed Class 450, and Speed Class 600) make it easier to identify and shop for an SD card. The number listed in each speed class denotes transfer speed in megabytes per second. A pill-shaped icon containing the letter “E” along with a speed class numeral will be printed on such cards.
The new SD 9.1 spec doesn’t have a launch date. Please note that a host device must support the SD 9.1 specification to make use of speed, thermal, and power improvements. For additional information, check out the SD 9.1 white paper or read the SD Association’s blog.