Lexar confirms that CFexpress cards run hotter than SD cards in cameras – and says it's an industry-wide challenge

Last November, Panasonic issued guidance regarding overheating issues on the Lumix S1II family of cameras. Along with a firmware fix, Panasonic reportedly advised creators to use SD cards rather than CFexpress as a way to manage heat issues. It was an unusual thing for a camera manufacturer to say in a briefing; essentially recommending a slower, older format over the newer, faster one that its own camera was designed to support.

The memory card industry, to my knowledge, didn't respond to this issue directly at the time. But recently, I had the opportunity to ask Lexar directly.

I was part of a small group of journalists invited to China to view the company's Zhongshan Storage Industrial Park and its Shenzhen innovation facilities. The access was extensive: production lines, quality testing labs, engineering briefings. There was also a press conference at which Lexar's senior representatives fielded questions from the group. I put the overheating question to them there, and the response was more forthcoming than I'd anticipated.

The back story

First, some context. One of the stops on our itinerary in Zhongshan, Guangdong province, was the Lexar Quality Lab: a long room lined with testing rigs, filled with the quiet hum of 1,200 devices simultaneously running storage media through its paces across every use case the engineering team could think of. Sony cameras, Nintendo Switch consoles, DJI drones, medical devices, dash cameras – if it takes a card, it was probably somewhere in that room.

The lab's purpose is to understand exactly how Lexar's products behave in the real world, across the full range of conditions users actually encounter. And thermal performance, it turns out, is something they think about rather a lot.

Their representatives confirmed that yes, SD cards have lower bandwidth and power consumption, while CFexpress cards generate more heat during operation. But that's not a design flaw: it's physics.

Higher data transfer speeds require more power, and more power generates more heat. The metal casings that characterise most CFexpress cards are not primarily an aesthetic choice; they're thermal management. Housing the card's components in aluminium rather than plastic gives the heat somewhere to go, allowing the card to sustain high transfer rates over longer periods without throttling or failing.

Whether that's sufficient when a camera body is itself running hot (a sensor, a processor, and a card slot all generating heat in close proximity) is evidently a more complicated question. Lexar stopped short of commenting on Panasonic's specific guidance, but the underlying physics they described validates the concern. If a camera body is already struggling thermally, adding a card that runs warmer than the alternative is not going to help.

Working on a solution

What struck me most, standing later in the testing lab watching cards cycle through endurance runs, was how actively this problem is being worked on. Lexar described a multi-pronged approach: developing controllers with lower power consumption, updating firmware to reduce unnecessary write activity, refining thermal management strategies, and redesigning the heat dissipation structure and materials of the cards themselves.

None of this was presented as imminent or finished: these are ongoing engineering problems rather than solved ones. But the frankness with which they were described was notable. Heat generation is "a common challenge across the industry," one rep said, in a way that suggested it's a daily conversation rather than an uncomfortable admission dragged out for journalists.

It's worth understanding why this matters beyond the specific case of one Panasonic camera. The trajectory of camera development is consistently toward higher resolutions, faster burst rates and more demanding video specifications. The Sony A1 II, the Canon R5 II, the Nikon Z6 III – all cameras I saw lined up in the testing lab, which have been put through their paces alongside Lexar's top-tier cards – are pushing data throughput to levels that would have seemed extraordinary five years ago. Each step up in specification increases the demand on the card, and therefore the heat generated during use.

The Panasonic situation may be the most publicly visible example of that tension so far, but it's unlikely to be the last. As cameras push toward 8K, higher frame rates and more complex computational tasks, the thermal envelope of current card formats will be tested more frequently. The engineers working on CFexpress cards know this. The question is whether the solutions (better materials, lower-power controllers, smarter firmware) can keep pace with what camera manufacturers are asking of them.

For the working photographer, particularly anyone using a high-end hybrid camera for extended video work, none of this changes the immediate calculus right now. A CFexpress card remains significantly faster than an SD card, and for cameras that support it, it remains the right choice for demanding applications.

But in the long term, it's worth knowing that its metal housing is doing real thermal work – and that the industry is aware the work is getting harder.