Best CFexpress Type-A Memory Cards – 18 Tested

CFexpress Type A (often abbreviated CFxA or CFeA) is the compact CFexpress format Sony uses in its newer full-frame mirrorless cameras. Below are 18 cards tested for burst and sustained write speed on an M4 Mac mini with AJA System Test, so you can see which ones hold their speed and which fall off once the SLC cache fills.

CFexpress Type-A cards are smaller but thicker and faster than UHS-II V90 SD memory cards.

Many CFexpress Type-A cards with larger capacities are now on the market, and their prices have decreased significantly. Some are now affordable enough to be considered a better value than V90 UHS-II SD memory cards.

Table of Contents

• New CF4.0 CFexpress Type-A Memory Cards
• CFexpress Type-A Memory Card Benchmarks
• What To Look For With CFexpress Type-A Cards
• How Are CFexpress Type A Cards Different Than CFexpress Type B?

New CF4.0 CFexpress Type-A Memory Cards

The CF4.0 interface is the latest technology in CFexpress Type-A memory cards. This new interface gives you about double the speed when accessing the flash on the card, but doesn’t increase the flash speed itself; it only reduces the access time. So when it comes to sustained speeds, our bottleneck is usually the slower flash type on the cards; this means it is mostly useful for photographers who burst a lot, since these cards mostly use the fast SLC-style cache.

No camera has yet taken advantage of this new standard. So, you don’t need to worry about buying CF4.0 cards if they are the most expensive. However, this is where everything is going, so if you find a great deal, you’ll have at least a card ready or a future camera.

CFexpress Type-A Memory Card Benchmarks

To find the best CFexpress Type-A memory cards, I benchmarked each with the AJA system test on an M4 Mac mini using the Prograde CFx CF4.0 Type-A reader.

AJA System Test settings: Resolution: 5120×2700 5k Red / Test File Size: 4GB For Burst, 128 or 64GB for Sustain / Codec Type 16bit RGBA. Speeds are shown in Megabytes per second.

AJA produces an average based on transfer request size for the codec type I’ve selected, so it is more relevant to camera usage, which is almost always sequential and often with larger write blocks. I run typically 3 tests and take the best results for the burst speeds. For the sustain speeds test I run 2 tests and take the worst results which usually happens at the second run after the card is hot.

Want the full write-up on a single card? See my Sony TOUGH CFexpress Type A review and my Lexar CFexpress Type A review.

You can see these benchmarked in various Sony Cameras.

Memory Cards For Sony A1 II

Memory Cards For Sony A9 III

Memory Card For Sony A1

Memory Card For Sony A7sIII

Memory Cards For Sony A7rV

Memory Card For Sony A7IV

You can check out this Sony Guide To Memory Cards to see which Sony cards support CFxA cards.

What To Look For With CFexpress Type-A Cards

These CFxA cars work similarly to the SSDs in our computers. They often use a fast SLC (Single-level cell) flash as an initial, quick cache that might be a few gigabytes. Once that cache fills up, the card starts writing to much slower memory, like MLC. This affects their sustain speeds.

You can see that working with the Sony Tough cards with the I/O transaction data below.

The faster SLC flash memory is initiated quickly, and write speeds are very quick, but once the SLC flash is filled, files and the fast cache write to slower memory until the SLC flash is cleared for another write cycle.

In addition, thermal throttling can occur when the cards get very hot. Although cards sometimes run better once they are a little warmed up. Flash memory likes being hot, but the controller inside it doesn’t.

To avoid negative reviews, memory card companies are now listing the guaranteed write speeds of these cards. For example, most CFxA cards list the 400 or 200-speed class. Similar to how we had V60 or V90 with our UHS-II SD cards.

If the card has a 400 rating (the little 400 inside the film clapboard), it is guaranteed to sustain an average of 400 MB/s.

How Are CFexpress Type A Cards Different Than CFexpress Type B?

The main difference between CFexpress Type A and CFExpress Type B cards, aside from their size, is that Type B cards have a two-lane bus for speeds up to 1700MB/s, while Type A cards have a one-lane bus for a top speed of 800MB/s.

With PCIe 4.0 now on the market, we can expect CFxA cards to get significantly faster. What’s cool is that we are starting to see PCIe 4.0 CFxA cards that are as fast as our current CF2.0 cards, CFxB cards, making this CFxA choice a pretty practical play by Sony, as the cards are much smaller and lighter. However, they could face more heat issues when running at blazing-fast PCIe 4.0 speeds on a single lane.