> For the complete documentation index, see [llms.txt](https://wiki.switchroot.org/wiki/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.switchroot.org/wiki/sd-card-guide.md). # SD Card Guide For explanations of terms used and a general lesson in the SD specs, jump to [#sd-card-terms](#sd-card-terms "mention") DISCLAIMER: Switchroot is neither affiliated nor associated with any SD card manufacturer, and our reviews are our opinions based on benchmarks, average binning, and other data we have collected. **TL;DR**: Get a UHS-I, U3, A2, V30, non-Express card, ideally Samsung, of 32GB or more ## 🚫 Broken, Fake, Scams The following cards should not be purchased--you have been warned! * Silicon Power (Taishin) * Many instances of fake and misleading listings * Also incompatible with DDR200 * Any card identified as `FAKE` under Hekate -> Console info -> microSD * If you bought one of these, try to refund! Amazon has been great about SD refunds. ## :warning: Problematic Cards ### Unknown Cards Any card identified as `UNKNOWN` under Hekate -> Console info -> microSD should be handled with scrutiny--this does not necessarily mean the card is fake or bad, but we have seen many cases where it is. Keep an eye out for the warning signs: * Model, OEM ID: are these fields empty or some fake-seeming string like `ASDF`? * Initial bus: is this anything slower than SDR104? * Capacity: is this substantially smaller than the labelled size? * Bear in mind MiB vs MB--storage manufacturers use MBs (bytes \* 1000 \* 1000) which is silly, hekate and most OS indicators use the original MiBs (the original MBs, bytes \* 1024 \*1024), see [this helpful Reddit comment](https://www.reddit.com/r/computerscience/comments/ccszjr/comment/etpo57s/?utm_source=share\&utm_medium=web3x\&utm_name=web3xcss\&utm_term=1\&utm_content=share_button) or [this great article from Corsair](https://www.corsair.com/us/en/explorer/diy-builder/storage/mebibyte-vs-megabyte-whats-the-difference/) * Bus width: is this anything but 4? * NOTE: this can also show as less than 4 due to common SD reader failures on V1/V2/Lite Switches * UHS Classes: is the rating something odd like `U0 V0 A0`? ### Problematic DDR200 See [#sd-card-terms](#sd-card-terms "mention") for DDR200 definition. DDR200 is enabled by default on L4T and optionally on Android (NOTE: currently Samsung cards enable by default on Android, we will soon remove this due to problematic SD Express cards). The cards below may fail to boot on Switch if DDR200 is enabled (they appear to work but on boot will either hang or corrupt your data): * Teamgroup * Foresee (Longsys) * Lexar (Longsys) * Samsung SD Express ### Poor Performance/Longevity These SD cards have been observed to have terrible performance, die quickly, or otherwise degrade from the experience. * SanDisk Ultra * SanDisk has had poor longevity and mediocre performance across the board, but the Ultras are a special breed of awful. You do not want one, don't bother. ## :white\_check\_mark: Recommended Cards ### Tier 1: Samsung T Series, PRO Series Highlights: * Fastest we've seen * Long life span * `ddr200` support * Good price-to-performance * Up to 1TB Samsung makes the best UHS-I microSD cards money can buy. The T9 (black, 2026) and T7 (blue, 2026) cards replace the PRO Ultimate (very dark blue, 2023-2025), PRO Endurance (white, 2018-2025), and PRO Plus (blue, 2015-2025) cards, so consider them interchangeable for this review. These cards are the fastest we've seen, and are (in all our testing) compatible the the `ddr200` specification as implemented in `hekate` and the L4T kernel. This goes beyond the 104 MB/s max of standard SDR104 and allows for the best performance possible on Switchroot operating systems. NOTES: * If you get PRO Plus cards, try to ensure they are [the blue 2023-2025 models](https://news.samsung.com/us/samsung-announces-improved-speeds-pro-plus-memory-card-line-up) with upgraded speed rather than [the striped original 2015 model](https://news.samsung.com/us/samsung-electronics-raises-the-bar-with-new-pro-plus-128gb-microsd-memory-card/)--this shouldn't be too difficult as the originals are very rare * We have not directly tested the T9/T7 cards directly, so please inform us if any info here is incorrect if you get one--some planned to purchase more cards for testing but the current flash storage pricing (2026) has made this difficult. However, all available info indicates these cards are just rebrands to bring naming in line with the P-series SD Express cards and T-series SSDs (though the latter is rather confusing). * Errata have been observed with some Pro Ultimate cards, with some reports indicating sustained transfers may cause slowdowns. They're not bad cards by any means, and should in theory last extremely long (plus have very long warranty), but we're not yet convinced they're worth the extra money over the Pro Plus line. * Do NOT buy Samsung's Express cards for Switchroot, as they are more expensive and do not support DDR200, and the Switch (unlike Switch 2) does not support the SD Express protocol, so you are stuck with the base backwards-compatible SDMMC speeds. ### Tier 2: Samsung EVO Series Highlights: * Moderately fast * Should support `ddr200` * Mediocre price-to-performance * Fairly available * Up to 1TB (but hard to find over 512GB) Samsung's EVO line is a bit below their PRO line in speed, quality, and longevity, but still a pretty good buy. While we have not specifically confirmed DDR200 support, these cards use fundamentally the same tech and should support as well (and they definitely do not have a system-breaking or corruption-inducing implementation). They are fairly easy to find and are a solid buy, especially if you wanted a T7/PRO Plus but they are out of price range or out of stock. NOTES: * Try to ensure they are [the white or blue gradient 2024-2026 models](https://news.samsung.com/us/samsung-announces-new-evo-select-evo-plus-microsd-cards-improved-speeds) with upgraded speed rather than the striped original 2015-2024 models ([EVO/EVO Plus](https://news.samsung.com/us/samsung-electronics-raises-the-bar-with-new-pro-plus-128gb-microsd-memory-card/), [EVO Select](https://www.amazon.com/Samsung-Electronics-microSDXC-Adapter-MB-ME256HA/dp/B0887P21Z2))--this is sometimes difficult as Amazon and other online retailers are FULL of the old ones. ### Tier 3: SanDisk Extreme, Extreme Pro, GamePlay Highlights: * Moderately fast * Good price-to-performance * Highly available * Relatively cheap * Up to 2TB SanDisk is the brand most people think of when they think of an SD card given their wide availability, decent prices, and high market share--but they come with many caveats. The first issue is lifespan--SanDisk cards will degrade quickly over time, and this can even lead to eventual write-locks and other failures. Another big caveat with SanDisk cards is their lack of L4T-compatible `ddr200` support, despite being the vendor that produced the specification originally. See the comment in [this commit](https://gitlab.com/switchroot/kernel/l4t-kernel-4.9/-/commit/92edf31455357f8d5f8bf882a747f42a49746ecf) for details. One last big SanDisk issue is branding--given their lack of year-specific branding and many SKUs, it can be hard to find a good SanDisk card. They also appear to be quietly dropping the A2 specification from their non-Express cards (Express never has A2), which is concerning as this likely means their random I/O is worse than it used to be. Our advice: Look for an Extreme, Extreme Pro, or GamePlay card that specifically lists A2 on the card. If you need higher capacity, you will likely be sacrificing performance, but this is a tradeoff for you to make. ## Contributing to the Guide Have a new card you don't see here or are having issues with? Contribute data by following our testing procedure: 1. Set up hekate 2. Ensure at least 1GiB of data has been written to the card to ensure results are accurate/representative 1. We recommend doing this by performing an eMMC RAW backup (Tools -> Backup eMMC -> eMMC RAW GPP) 3. Perform a microSD card benchmark (Console Info -> microSD -> Benchmark) and take a screenshot of the results 4. Select 'OK' and take a screenshot of the microSD Card Info page 1. The order is key here as the benchmark can reveal errors or other issues that will be logged in the microSD Card Info page 5. Share the screenshots in our Discord ## SD Card Terms * HS refers to the High Speed bus for SD cards, which is no longer actually considered very fast (similar to "Fast Ethernet"). * UHS refers to the Ultra High Speed bus for SD cards, with a Roman numeral suffix for the revision. UHS-I refers to the original UHS SD specification with the standard one row of pins. UHS-II and -III achieve faster speeds with more contacts, but the Switch's microSD reader is limited to UHS-I, as most readers in such devices are. * SD Express is a newer bus that enables a PCIe-NVMe interface in an SD/microSD form factor. SD Express is NOT supported on the Switch, but is supported on the Switch 2 to support the higher demands of its games. Cards supporting the SD Express bus (which we often just refer to as SD Express cards) generally support the UHS-I bus as a backup, but just for backwards compatibility, so they generally don't support nice features like DDR200.

Bus Speed chart, credit https://www.sdcard.org/developers/sd-standard-overview/bus-speed-default-speed-high-speed-uhs-sd-express/

* `ddr200` is essentially the SD version of the eMMC HS400 standard, created by SanDisk, to essentially allow close to double the SDR104 throughput over the UHS-I bus. However, their reference implementation required a DLL mechanism that is not supported on the Switch's reader. Every other vendor that supports the standard aligns transfers on clock edge instead of whenever based on the DLL mechanism, allowing `ddr200` to work on these cards as a version of SDR104 (normally the fastest speed spec for this reader) that samples on rising and falling edge. See the comment in [this commit](https://gitlab.com/switchroot/kernel/l4t-kernel-4.9/-/commit/92edf31455357f8d5f8bf882a747f42a49746ecf) from CTCaer for details.

Snapshot from "SanDisk QuickFlow" tech brief, credit https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/collateral/tech-brief/tech-brief-sandisk-quickflow-technology.pdf

* The A rating, or Application Performance Class, is defined by the SD Association as a standard for minimum general IO performance. This is intended to differentiate cards that are better for storage operations. The A2 rating necessitates a minimum random read speed of 4000 IOPS, a minimum random write speed of 2000 IOPS, and a minimum sustained sequential write speed of 10 MB/s. We recommend cards used for running Switchroot operating systems should be A2, but note that A2 has (or at least had when A2 was initially added to the SD spec) specific hardware requirements that SD Express cards generally don't need/support in order to sustain these performance targets. That does NOT mean that SD Express cards do not support A2 random I/O performance.

Snapshot from Application Performance Class chart, credit https://www.sdcard.org/developers/sd-standard-overview/application-performance-class/

* The C, U, and V ratings, or HS Speed Class, UHS Speed Class, and Video Speed Class, are defined by the SD Association as a standard for minimum sequential write speed. This is intended to differentiate cards that are better for applications like filming video, where the relevant storage operations are generally sequential. This is not relevant for us because the bottleneck in running operating systems off of an SD card is generally random IO performance rather than sequential, so if you have a C10 U3 V30 (above V30 requires UHS-II or -III) card that is only A1, you will likely have a poor experience. Note that HS and UHS are not the same, so a U1 card must be UHS-I and be HS class 10, but a HS class 10 card does not have support UHS, and in that case would not be U1. SD Express has the E150-E600 classes, but we rarely see these written directly on the cards these days, likely because the modern ones all just have the EX label and support 800MB/s.

Speed Class chart, credit https://www.sdcard.org/developers/sd-standard-overview/speed-class/

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