SanDisk Extreme Pro 512GB CFExpress B Card Review – Understanding Sustained Data Transfer, Temperatures and Thermal Throttling


CFexpress is still a relatively new storage medium and it’s performance has changed the way we look at cameras today.  The Canon EOS R5 could not have been marketed with any other card but CFexpress.  For media professionals, it is a game changing camera  leaving behind the thought of filled buffers and single digit FPS, while at the same time bringing us the highest resolution 4K and even 8K video.  A tad amusing perhaps are the threads found on various forums from those trying to price out 8K media capable PC systems.

The SanDisk Extreme Pro CFexpress B Card is available in several capacities and fully capable of speeds up to 1700MB/s read and 1400MB/s write.  We have demonstrated its sustained write performance of 751MB/s which is far more than the minimum 400MB/s required by the R5.  Pricing is pretty much as can be expected from the Extreme Pro as CFexpress is still very niche and has become very much a necessity for some, however, the limited lifetime warranty helps somewhat.


Our findings with respect to card temperature and thermal throttling were very interesting.  The SanDisk Extreme Pro thermal throttles at 65C and drops its speeds to just above that of the minimum required by the EOS R5 itself.  Although we can’t answer the question as to what pushes the r5 into overheating mode, it is a given that CFexpress gets hot considering the data and speed of that data being moved simultaneous to recording.  Don’t be surprised if we see a manufacturer introduce a ‘LP’ (low power) version of a CFexpress B card soon enough.

Check SanDisk Extreme Pro CFexpress B Pricing at Amazon.




SanDisk Extreme Pro CFexpress B Card Ratings

Product Build
Lifetime Warranty
Pricing and Availability


The SanDisk Extreme Pro CFexpress B Card is a proven reliable card that reaches capacities up to 1700MB/s and has a limited lifetime warranty. It also has sustained write speeds of 750MB/s

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