Real or Fake? The Lexar 600x 64Gb MicroSDXC Card Mystery

A few weeks back, eBay had a 15% off everything sale on a Sunday, and I was feeling like I needed to make the most of it. There wasn’t too many things I could really need but I did decide that a few large microSDXC cards wouldn’t go astray.

I was looking for something with a decent amount of performance and a reasonable price, and a side positive was if it was not already tested, because that means another blog post for all of you.

I came across a Lexar 600x 64Gb MicroSDXC card from an eBay seller with >99% positive feedback who will remain unnamed, for a decent, but not unreasonable price. The cards were advertised as:

Lexar Ultra 600x 64GB Micro SDXC Memory Card
Genuine Lexar card!!! Bulk package in mini plastic case.

I had to buy two to make the 15% offer, so I put in an order for two. After all, Lexar is a reputable brand, and I definitely have no Lexar cards in my collection at the moment. A little bit of homework showed that the product itself was given a press release on Lexar’s website, so it’s not as if it was entirely made up.

It Arrives!

From past experience, if you get a fake, you’d recognize it right away. Poor quality faded silkscreening, logos with wonky proportions, text which isn’t straight or font changes are just some of the imperfections many fake cards have. Another difference is the rear etchings. As a result, I paid good attention to examine the cards themselves.

DSC_8184 DSC_8186

The silkscreen text was a very sharp, bright white, and it looked good. A review of an updated 633x card, which is part of their present lineup, shows rear markings that match the same formatting and are made in the same place. Looks good so far.

The two cards’ CID and CSD details are as follows:

cid: 284245202020202001bb193b6700da5b
csd: 400e00325b590001dd3d7f800a40001d

cid: 284245202020202001bc182a4500dad5
csd: 400e00325b590001dd3d7f800a40001d

I don’t have any Lexar cards to compare to, but checking the database shows the Vendor ID doesn’t match with any of those within the database, and the CIDs are unique due to differences in serial number, which is another positive sign. The product string is just a sequence of spaces (0x20), but that isn’t entirely unusual given that other cards have similar results.

Lets get along and start reviewing the card as per usual then …

Performance Testing

Filling the entire card surface with random data didn’t pose any problems at all. Reading it back resulted in the same values every time as well.

HD Tune Pro with Transcend RDF8


The card doesn’t make it to the 95Mb/s that is claimed, and averages 64.3Mb/s which is quite a distance from the stated speed. I would expect about 83Mb/s judging from the contemporary 90Mb/s+ cards. Hmm.

HD Tune Pro with Kogan RTS5301


Placing the card into the reader bare failed to negotiate UHS-I mode, so the transfer rate was capped at 22.5Mb/s. Lets try using a microSD to SD adapter:


With the adapter, the card averaged 51.9Mb/s, again, falling short of the promised speeds. Given that most cards excel strongly at sequential read, this is hard to believe.

CrystalDiskMark with Transcend RDF8


Using CrystalDiskMark, the card does now reach 83.58Mb/s which is in the ballpark of other 95Mb/s cards previously tested. The other speed scores are not too bad, and are in fact quite good.

CrystalDiskMark with Kogan RTS5301


Unfortunately, it seems that the Realtek-based reader wasn’t able to extract full performance from this card.

The Trouble Begins

Imagine my surprise when, after all of this, and never having seen this before … I get this:


Yikes. H2testw believes the card is defective, with the original factory formatting, losing 2.7 Megabytes of data. The full text is as follows:

Warning: Only 61054 of 61055 MByte tested.
The media is likely to be defective.
59.6 GByte OK (125032884 sectors)
2.7 MByte DATA LOST (5708 sectors)
Details:0 KByte overwritten (0 sectors)
0 KByte slightly changed (< 8 bit/sector, 0 sectors)
2.7 MByte corrupted (5708 sectors)
0 KByte aliased memory (0 sectors)
First error at offset: 0x0000000149faa000
Expected: 0x0000000149faa000
Found: 0x000000014dfaa000
H2testw version 1.3
Writing speed: 42.0 MByte/s
Reading speed: 72.7 MByte/s
H2testw v1.4

Having thought this might be because the card was incorrectly formatted (oversized), I reformatted it with SDFormatter with the size adjustment on, and data overwrite.


It still did not pass. The full report is as follows:

Warning: Only 61050 of 61051 MByte tested.
The media is likely to be defective.
59.6 GByte OK (125030032 sectors)
184 KByte DATA LOST (368 sectors)
Details:0 KByte overwritten (0 sectors)
0 KByte slightly changed (< 8 bit/sector, 0 sectors)
184 KByte corrupted (368 sectors)
0 KByte aliased memory (0 sectors)
First error at offset: 0x00000002fafaa008
Expected: 0xfafaa02cb4af6011
Found: 0xfafaa02cb4af6001
H2testw version 1.3
Writing speed: 43.1 MByte/s
Reading speed: 73.0 MByte/s
H2testw v1.4

Notably a smaller amount was lost, but it really should be nothing. It’s even more interesting to see that the data was not lost at the end of the card but somewhere near the 4Gb mark.

Bouyed by this, I decided to random fill the card a few times, then reformat it again to see if I can recover the corrupted sectors. After another format, the results seem to show less failing memory.


Trying it again …. and nope. It seems to have made it slightly worse again!


After this, I did a pattern fill on the card and examined the corrupted areas. To my surprise they contained random data and were not sector aligned. That is very curious, given the nature of flash normally using pages with a size of a binary power. Maybe this indicates a dud controller, failures in the flash translation layer, the use of some compression. Another thing is that it seems that the controller being configured not to report errors even though a read is entirely ECC uncorrectable. This may make a user’s job easier in recovering from a dud card, but it masks the problems and causes silent bit-rot, which wasn’t detected by a random fill and multiple read-back test.

corruption-not-on-sec-boundaries corruption-not-on-sec-boundaries2

After that, I gave it a format … and … miraculously, the card now holds data correctly!


But that’s not where the story ends … I was still skeptical about this card – the read performance has dropped dramatically from 72.7Mb/s to 67.0Mb/s. What the hell is going on. I decide to give it another few passes … and then … it locked up on me.


The card behaved as if it was write protected, regardless of reader. I even tried using a direct slot on the Samsung ARM Chromebook and couldn’t force any writes. Instead it held the last bit of data that I had put onto it … and that was all.

This seems to be indicative that the card has entirely run out of remappable flash sectors to the point it had exhausted all spare sectors and could not continue to function, dropping back into read-only mode to allow users to recover their files and move on to another card. All of this happened in under 10 cycles.

The Mystery Deepens

This is where the “sister” card gets involved. It turns out, the sister card itself was happy, and easily passed five cycles of H2testw even with its original format.

lexar600-sample2-preformat-h2tw lexar600-sample2-preformat-h2tw2

The read performance didn’t decline or waver as much. But the card still didn’t quite show the 95Mb/s read performance that I would have expected. My confidence in the status of the cards is still shaken, and thus the results are not going to be included in the database.

It seems this is a very peculiar situation with several possibilities:

  • It’s a counterfeit card, elaborately silk-screened and laser etched to meet the original’s in terms of appearance.
  • It’s a defective genuine card that may have “escaped” destruction at some stage.
  • It is a genuine card, albeit a bad sample that evaded quality control.

Lets consider each of these possibilities in turn:

  • Generally, counterfeit cards seek to maximise profit – there isn’t much to be gained by using what appears to be a real 64Gb card to counterfeit a 64Gb card. The cost of a 64Gb card is not insignificant. Instead, maybe by remarking a lower-performance card as a higher performance card, they can gain some money, but by card standards, this card wasn’t too bad in terms of performance. Maybe they got some OEM cards from a different vendor and remarked them to look like Lexar for some quick bucks. It’s a lot of work though.
  • I think it’s possible, although a supply of defective genuine cards is rather limited. My assumption is that most defects are likely caught early in production before they are properly branded and marked.
  • Also a possibility, although the performance makes me question whether it’s a genuine card at all. The only way to tell for sure would be to decapsulate the card and image the die, or try some X-ray photography, none of which I have at my disposal.

Regardless, this isn’t a card I can trust.


I think the message is to test and be wary of any products you receive. You should always test your hardware before commissioning it to catch these sorts of issues. While I can’t conclusively say the card is a counterfeit, it definitely appears to be defective. The way the card corrupted data was also rather surprising, and it’s not behaviour I would expect from a Lexar card at all. The fact it took numerous overwrites for the (supposed) reallocations to occur suggest something strange going on. The write protected status in the end indicates the card itself was having an internal struggle of its own.

It has shaken my confidence in buying cards on eBay even from sellers with high positive feedback scores, specializing in memory products. I managed to return the two cards (at my cost) for a full refund, but lets just say, this was not a positive experience. I suppose you should always be wary, especially of “bulk packaged” items.

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
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20 Responses to Real or Fake? The Lexar 600x 64Gb MicroSDXC Card Mystery

  1. Jaime says:

    i had the same experience buying sd cards from e-bay i’m not an e-bay buyer any more cause is must of things that i got from e-bay are garbage

  2. sediriw says:

    For more in depth look at the SD card industry, check out Andrew ‘Bunnie’ Huang’s blog post

    • lui_gough says:

      I’ve actually seen that post a long time ago, and it was part of the inspiration for testing, checking and recording the CSD and CID values for each of the cards I’ve regularly handled. Unfortunately, I don’t have the equipment to properly decapsulate and image the dies of the cards, but it definitely would prove to be a very interesting exercise.

      – Gough

  3. Peter Paul says:

    Too bad there is no way from Lexar’s site to counter check the serial numbers to determine whether its legit or not. Some company offers a way for customers to counter check the items.

    • Jason B says:

      I agree. I just ordered a 64 GB class 10 Lexar microSD card from Amazon (Prime) but I just realized that it’s only Amazon shipping it for a 3rd party. I will definitely be testing it when I receive it.

  4. JeffComputerTech says:

    I had the exact same problems with their media , both received from Adorama, and DIRECT from LEXAR
    I have so far tested 9 of the 633x cards
    about 1/2 fail the H2testw test.
    I have had 3 that became write protected.
    1 of the 3 worked like above then suddenly became permanently write protected.
    1 of the 3 was a replacement for a 64gb card from their rma dept. It was write protected when I received it from them.
    1 of the 3 was from a new in retail packaged 64gb card. again – WPOA (Write Protected On Arrival. )

    Any one else experience this?
    From my results – these are VERY bad cards.

    When the 64gb was sent back to them , their testing lab reported the card worked fine for them.
    I had tried it on 4 computers , 3 different types of micorsd adapters – usb 3 , miscosd to sd card , microsd to usb 2.0 ALL REPORTED WRITE PROTECTED

    • lui_gough says:

      It sounds like Lexar doesn’t know what they’re doing. How very sad, as they are generally highly regarded as the second to Sandisk when it comes to professional flash cards.

      Assuming you are not using a microSD to SD adapter with a write protect switch, the write protection is definitely the card “giving up” and refusing write commands, and is a hardware issue with the card itself. It seems like their own RMA department just plugs it in, sees it come up, and calls it okay. Definitely something wrong with what’s going on if you’re having so much trouble with them too.

      Thanks for letting us know your experiences.

      – Gough

  5. JeffComputerTech says:

    It appears even though it is write protected, you can delete the partition, and recreate it. ( at least on the one currently in my possession .) Then you can write to the card.

    • lui_gough says:

      Hmm. Mine wasn’t so forgiving. I couldn’t even address it raw as a block device under Linux and get DD to zero out the partition table, so mine was a “hard” failure. Lets hope it doesn’t develop any further problems.

      – Gough

      • JeffComputerTech says:

        what type of reader are you using? I am using a Lexar microsd to usb 3.0 adapter.

        • lui_gough says:

          I normally use a Transcend RDF8 USB 3.0 reader, based around a Genesys Logic chipset. When that fails, I fall back to an unbranded USB 3.0 reader based around a Realtek chipset … If all else fails, I have a Chromebook with a hardware SD slot running Linux that can talk to the cards directly, and a Transcend USB 2.0 reader based on the Alcor Micro chipset.

          I’ve known well enough from compatibility shenanegans to keep more than a few different chipsets on hand, because they often perform differently.

          – Gough

          • JeffComputerTech says:

            I understand, I do the same thing, keeping different readers handy.
            For my issue I am dealing with one of the higher ups in Lexar usa. The last “batch” of bad ones I sent to them, he sent to their testing lab. They told him they could write to the microsd card no problem. They failed to mention they deleted the partition and reformatted it.
            Previously when I had the 1st card that became write protected DURING USE, the tech support dept said that meant the drive went bad.
            So I never bothered to delete the partition.
            On a later rma exchange, I got a replacement card that was write protected with nothing on it. I just tried to write to it on different devices / computers, not delete partition. That was the drive they said had no problem.

            The I got two new in package drives and one of the two was blank and write protected out of the package. When partition deleted, and new one made, the drive could be written to. The other drive worked ok on same computers.

            Side note concerning the readers from Lexar.
            In testing 12 Lexar Microsd to usb 3.0 adapters,
            Note – these were physical issues vs electrical / coding compatibility .

            I found some Lexar microsd to usb adapters that were defective when made.
            one had to be 1/2 out to be detected / work in some usb ports. I have never had a usb device have this issue. This issue only afflicted some usb ports.

            Four (4) did not detect any thinner media other than the 633x which is 25 units thick while other cards are 23 units thick. I do not have any thick microsd cards other than 633x cards to test with.

  6. JeffComputerTech says:

    New issue. One of my Lexar 633x cards. I use it to record videos on a go pro. when I go to copy files off later, one gets messed up. . But only one. I will have to run an extensive check of the the card, but I expect to have to RMA it.

  7. My first Lexar 633x card locked up and then I ordered another one intending to send the first one back. Then the second one locked up but the first one, after reformatting in my Inspire 1 drone , started to work. I was all set to send the second one back but then they both locked up. After reading the prior comments from some rather brilliant testers I think it may be the reader causing the problems. I use the cards in my Inspire 1 drones and depend on them to capture my flight videos. After reformatting them in my drone camera, one worked and the other refused to be reformatted, claiming it was write protected.Very frustrating! Thanks for all your brilliant advice.

  8. ChrisM says:

    I’ve just had a 200GB Lexar 633x card malfunction . . . unable to write, erase, reformat or delete files from it. Have tried everything and still no joy, but I did use SD Insight on my Android phone and that revealed it was a 201GB capacity card manufactured by Barun Electronics . . . thought Lexar manufactured their own cards. Makes me believe it is not a genuine Lexar card, and it was bought from Amazon July 2017 . . . think I will be in touch with them regarding a refund.

    • Mike Hawk says:

      I was not aware anyone made a 200gb card. I have seen 256gb but not 200gb.
      as for who to contact, maybe you should contact the maker before Amazon.

      • Mike Hawk says:

        I looked it up I was surprised 200gb existed. I never noticed them in any store I was at. But then again I am mainly looking at 128 gb as my go pro only supports upto to that size. and ads for memory mainly focus on 64 128 256. So a memory card made of a 128 and 64 mb is still a surprise.
        I wonder if a 200gb would work in a go pro 4 ? anyone know?

  9. Mike Hawk says:

    I sent one into Lexar for RMA. mine was a u3 card
    the replacement was u1 .
    I contacted them as soon as received back.

    1st they denied I had sent in a u3 card. I emailed them pics
    then They said they no longer made u3 cards only u1
    I gave them the pare number of a u3 card listed on their site as still current. also checked and it was foe sale at most places.
    they said they cannot replace a slower card with a faster one. They can only replace a faster card with a slower one.
    then they refused to replace the slower card with a faster one of u3.
    Then I filed in small claims court 1 week later.

    two weeks later they sent me a letter saying I was stupid for thinking I should expect to get a u3 card since they have discontinued the u3 card . The letter went on to say other stuff. Everything in the letter was great. it was like a confession in writing from them. I cannot wait to go to court. I am now hoping for triple damages since it is intentional. .

    • yet another lexar user :) says:

      This is crazy. This is an actual Lexar reply? “We wont honour a return cos we have discontinued the product but it still is sold on the shelves”?!!

  10. yet another lexar user :) says:

    To wit, I have ordered (and using) cards from ebay (might even be from the same seller as you), and found the cards sometimes go askew on my camera. I had assumed it was my camera that needed servicing, as it was a few years old(d90).
    Now it might be that the cards are not so, how do you put it, resilient to usage? Or have limited read-write cycles?
    Unlike say Sandisk? These are called “professional” cards fwiw.

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