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A few years back we did a preview article on a new controller card by Silicon Motion named the SM2708. This controller was originally tested with an engineering sample SDXC ‘Express’ card and returned speeds just below 900MB/s which was in line with the newest SD Association SD7.x standard. To clarify, SD 7.0 pertains to SDXC cards while SD 7.1 speaks to microSD cards, both enabling speeds up to 900MB/s through use of a single Gen3 PCIe lane. SD8.x will push even further as it enables the use of two Gen4 lanes for a speed maximum of just under 4GB/s.
It has been some time since we posted that article, and most recently, we are finally seeing the newest SD Express iimplementation with release of the Nintendo Switch 2 Gaming console. This console has a microSD Express slot (same form factor as microSD) on its base that is compatible with only the newest microSDXC Express cards.
We have scoured the internet and have yet to find any posted speeds for the few cards that are out and very limited performance testing, so we thought we might step up to bat, so to speak. With respect to the Switch 2, we can conduct three specific tests, data transfer to and from the micro SDXC Express card, as well as game load times while the Switch 2 is operating the game from the card itself.
Quite frankly, it is absolutely amazing that a storage device the size of a microSD card could even contain an SD controller, much less enable PCIe 3.0 single lane speeds up to 900MB/s. Hence the name microSDXC ‘Express’. This photo is a Canadian dime, which is exactly the same size of an American dime… although its value is some 40% less.
Our report today is on the ADATA Premier Extreme 256GB SDXC 256GB SDXC Express Card and we can see from the picture above that it follows SD7.1 standards , and further, we see a new ‘EX 1″ which denotes that this is an SD Express card. Listed performance for this card 800MB/s read and 700MB/s write, given consideratiion that this is also backward compatible to UHS-1 U3 Class 10 standards.
We can see new ‘E150-600’ symbols implemented from the SD Association for SD Express cards but we are not seeing them on new cards to date.
Checking Amazon, we can find the ADATA 256 GB Premier Extreme microSDXC Express card priced at $59.99, while the 512GB version is on sale at the time of this report for $50 off at $99.99. Let’s check out some speeds.