Lexar Professional 1000x 64GB

Oh boy, do I have a thing or two to say about these cards. So here we go.

I purchased sample #1 because I wanted to be able to have at least one UHS-II card in my results. (At that point in time, I hadn’t made the decision to test at least three of each model of card.) UHS-II cards tend to be pretty expensive (comparatively speaking), which is why I initially only ordered one. It came in retail packaging, complete with a Lexar LRWM05U-7000 UHS-II card reader, and I initially planned to test it with this card reader — but fate (or Lexar?) apparently had other ideas. It almost immediately had issues and was unable to make it through even its authenticity or performance tests. After a few tries, I was able to get it to complete both tests — but I found that it was much more stable when I switched it over to another reader, so I gave up on the Lexar reader and put it into a JJC CR-UTC4AC instead.

The I/O errors stopped under the JJC reader, but then a different issue surfaced: in every round of the endurance test, there would be a handful of data verification failures. But when I looked at the data being read back and compared it to what was being written to the card, I noticed something odd. Here’s a snippet of my logs — see if you can spot the issue:

And another mismatch that happened a couple weeks later:

See that? It’s always bytes 16-19 that are mismatched. Every. Single. Time.

“OK”, I thought to myself, “maybe I just got a bad card. It happens. I’ll just order another one.” So I did, and from the same Amazon seller. This one looked pretty much identical to the first one, complete with another Lexar LRWM05U-7000 card reader. This time, I decided to set that reader aside and put it straight into one of the JJC CR-UTC4AC readers. And as soon as the endurance test started running? It started having the same issue — right down to the same four bytes being mismatched:

This was too weird to be coincidence. I considered that maybe they were both part of the same batch, and that there was an issue with that particular batch — but the two cards have different manufacturing dates (and wildly different serial numbers). That means that either there was a manufacturing issue that went undetected for multiple batches, or there’s a design flaw with this card.

For a while, I was going to leave it at that; but at some point, I decided that I should try to have at least three samples of all the cards I’m testing — so I went back to the same Amazon seller and ordered a third one. Here’s where the story took a twist: the product packaging was identical, it included another Lexar LRWM05U-7000 card reader, the card design was the same — but the etchings on the back of the card were different, and the CID data indicated that it was a completely different card! Every single field in the CID register was different from the other two samples. The manufacturer ID indicates that it was made by Phison — which has been known to make Lexar-branded cards in the past (at least, according to CameraMemorySpeed.com) — so my guess is that Lexar simply contracted out part of the production of these cards to Phison. This card has not had the same issues that the two Micron-produced samples did.

On the performance front: the package advertises read speeds of up to 150MB/sec and write speeds of up to 45MB/sec. All three samples managed to surpass 150MB/sec on sequential read speeds, but only sample #3 (the Phison-produced sample) managed to hit the 45MB/sec mark on sequential write speeds. Here’s how things shook out:

• Sequential read: There was a little bit of a spread in the scores (about 19MB/sec between the three), but all three scores fell between the 95th and 99th percentiles (as of the time of this writing).
• Sequential write: Sample #3 (the Phison-produced sample) did the best here, scoring in the 83rd percentile. The other two scored in the 62nd and 63rd percentiles.
• Random read: Results here were pretty inconsistent between the three samples, with sample #2 doing significantly worse than the other two — it score placed it in the 15th percentile. Sample #3 scored in the 74th percentile, while sample #1 scored in the 94th percentile.
• Random write: Again, results here were pretty inconsistent between the three samples. Sample #3 did the best, scoring in the 77th percentile; sample #2 scored in the 26th percentile, while sample #1 scored in just the 16th percentile.

All three samples scored well enough to merit the Class 10 and U3 markings; but frankly, I would have expected better for a name-brand card that had “Professional” as part of its name — especially when there are UHS-I cards that were able to perform better.

On the endurance testing front:

• Sample #1 has survived 8,679 read/write cycles so far.
• Sample #2 has survived 9,408 read/write cycles so far. (I find it curious that sample #2 has outpaced sample #1 — they’re both hooked up to the same machine, to identical card readers. However, sample #1 is averaging about 9.14 read/write cycles per day, while sample #2 is averaging about 14.85 read/write cycles per day. I don’t know why.)
• Sample #3’s first error was a 4-sector wide address decoding error that occurred during round 164. It has survived 6,317 read/write cycles in total so far.

Overall, however, I wouldn’t recommend buying this card. While some of the performance metrics were good-to-impressive, it doesn’t make up for the data integrity issues that I encountered on the two Lexar-produced samples. As evidenced by the fact that I bought all three samples from the same seller and got two different cards, I think it’s fair to say that if you purchased one of these, there would be no way of knowing beforehand whether you were going to get a Lexar-produced card or a Phison-produced card. Had I used this in a digital camera and gone on a photo shoot, it’s likely that some of my pictures would have been corrupted the very first time I used the card — and any photographer will tell you that’s just not acceptable. I think I’m going to have to say “don’t buy these”.

June 17, 2025 (current number of read/write cycles is updated automatically every hour)