Lexar Professional Diamond CFExpress Card Review



Two characteristics that became very important with the introduction of CFexpress as a mainstream storage medium were temperature and sustained write speeds.  We measure temperature by monitoring and updating a  Crystal DiskInfo Benchmark while a large 85GB 8K file transfer is being performed.  This is the extreme of what one might see in this environment.

An important aspect to remember is that the temperature results we obtain are the extreme.  They are the hottest the card got during any period of our testing which was constantly monitored.  It does not speak to the median or typical temperatures one might expect which would be around the low 30°C mark.  Having said that, the results we obtained from the Lexar Professional Diamond Series 128GB CFExpress Type B card were a bit high in comparison to what we are seeing in other recent competitor releases.


We determine sustained write performance by transferring a 85GB 8K media folder from the PC to the CFexpress Type B card.  This test is vital to those looking at digital storage for high end 4K and 8K video recording.

Although we hope to see a very smooth and steady sustained write speed during data transfer, the sustained write speed of 1.53GB/s is the best we have seen to date and just below listed specifications of 1.6GB/s.


For our Real World File Transfer Comparison of the world’s top CFexpress Type B cards, we have included all cards that we have received to date. This test is conducted through the transfer of data from one spot on the test drive to another to give us the truest of transfer speed results for that device.

The Data Transfer speed of the Lexar Professional Diamond Series 128GB CFExpress type B Memory Card is the best we have seen to date and consistent with what we are seeing throughout our overall test regimen.


When we started this report, we envisioned providing an understanding of how manufacturers market storage products through use of high sequential read and write speeds.  This is an unfortunate reality and, in all actuality, most users might only ever reach these speeds less than 1% of the time.  As much as it seems deceiving and we don’t like it, it really isn’t as we see the same type of marketing in so many product sales.  Our goal then became one in which we wanted to provided an understanding of the three constants of a high quality CFexpress Type B memory card; data transfer and sustained write speeds, along with maximum operating card temperature.

We test those variables each and every time, as well as confirming that the card is capable of the specifications listed by the company.  As much as our testing today demonstrated that the Lexar Professional CFExpress Type B 128 GB Diamond Series Card met those standards, the card stepped out from the pack.  Not only is its high sequential read and write performance of 1876MB/s read and 1683MB/s write the best we have seen to date, but also, the Lexar Diamond proved that it was ‘Top Dog’ as well in sustained write performance with a high of 1.53GB/s as well as our Real World File Transfer testing.

The only hiccup we might suggest in all of our testing is the temperature of 68°C which still comes nowhere near what we have seen with some of the more successful cards in the past.  This is also nowhere near where one might thing a storage product would throttle, if in fact it was set up as such. I personally wouldn’t worry about it whatsoever and, in fact, it is in my R5 for a bit of extensive testing right now.  Lexar Professional Diamond Series Cards come with a limited lifetime warranty which is simply icing on the cake.  Availability… As this card has just been released, we aren’t seeing it in Amazon just yet but have found it elsewhere for $199 (128GB) and $329 (256GB) which is a bit high but a price we might expect from what just might be the industries best!

Check for Lexar Pro CFExpress B Diamond Series Pricing at Amazon

Lexar Pro Type B Diamond Memory Card Review

Product Build
Lifetime Warranty
Price and Availability

Industry leading Speeds!

The Lexar Professional CFExpress Type B Diamond Series Memory Card Family have the best sequential and sustained write performance, as well as data transfer comparisons that we have seen to date. The inclusion of a lifetime limited warranty makes this card a 'must have' for camera professionals.

Check Amazon
User Rating: 1.94 ( 2 votes)

Leave a Reply