Mega benchmarks of SD cards


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Interesting stuff. The site with the overview: https://www.bahjeez.com/the-great-microsd-card-survey/

The average best cards:
  1. Kingston Canvas Go! Plus 64GB
  2. PNY PRO Elite Prime 64GB
  3. SanDisk Extreme 64GB
  4. PNY Premier-X 128GB
  5. Delkin Devices HYPERSPEED 128GB
  6. HP MicroSDXC mx330 64GB
  7. Kioxia Exceria G2 64GB

Other learnings:
  • Capacity:
    • Skimp is a problem across the industry. The only brand that was consistently not skimpy was Samsung.
    • Many card brands offer cards in various capacities. When you look at prices for authentic flash, price will generally scale up as capacity goes up. (This doesn’t always hold true for smaller cards — but it almost always holds true for larger cards.) When you look at fake flash, however, the prices will generally be pretty similar — usually within about $1 of each other — regardless of the capacity.
    • As of this writing, there’s only one model of 2TB microSD card known to exist — and that’s the Kioxia Exceria Plus G2. If you see a 2TB card and it’s not a Kioxia Exceria Plus G2, there’s a 100% chance that it’s fake.
    • There are brands that will sell both fake flash and authentic flash. Usually, smaller sizes will be authentic, while larger sizes will be fake — but there are exceptions to this.
  • Performance:
    • Almost all new microSD cards today support UHS-I. Under UHS-I, the maximum possible transfer rate should be 104MB/sec (although in actuality, the maximum transfer rate will be a little less than this).
    • Fake flash cards usually tends to fall far short of this limit.
    • Most off-brand flash cards, and many name-brand flash cards, get close to this limit — probably as close as they can feasibly get when you factor in the time needed to issue commands, the time needed to transfer preambles/CRCs, etc. — at least in sequential read speeds. Most cards didn’t even get halfway to this mark with their sequential write speeds.
    • SanDisk managed to figure out how to go over this limit — I haven’t figured out exactly how they do it, but I suspect that their trick is simply providing a faster clock signal to the card. It does, however, require both a card and a reader that support these faster transfer rates. And, while SanDisk led the way here, other brands seem to be following — including Kingston and Samsung.
  • Endurance:
    • Fake flash cards (unsurprisingly) tends to fail earlier than authentic flash cards. There are isolated exceptions to this, but when it happens, it tends to be just that — an exception to the rule.
    • Name-brand flash, off-brand flash, and fake flash all tend to fail in different ways.
      • Fake flash cards tends to start exhibiting bit flip errors early on. Generally, once you see your first error on a fake flash card, the number of errors (per read/write cycle) only goes up from there.
      • Off-brand cards do tend to follow this same pattern, although the first error tends to happen later than it does with fake flash cards. This could be an indication that off-brand cards use higher quality flash media than fake flash cards.
      • Name-brand flash doesn’t necessarily last any longer than off-brand flash before experiencing its first error. However, errors with name-brand flash generally tend to be fewer and farther between. I believe this is because name-brand flash usually employs error correction and wear leveling techniques that help reduce the frequency of errors. Name-brand flash does tend to be more susceptible to address decoding errors — and I don’t know yet whether those errors could be resolved by trying to re-read the affected sector or not.
 
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