CFexpress has emerged as the go-to memory card format for most professional cameras today, coming in two popular formats: CFexpress Type-A and CFexpress Type-B.
Not only have CFexpress cards surpassed V90 UHS-II SD cards in speed and performance, but they can sometimes even be found at a better price. However, CFexpress 4.0 bridges this performance gap even further.
This article will explore benchmarks and why these cards are worth your attention.
CFexpress Type B vs. Type A
Before we delve into the specifics of CFexpress 4.0, let’s clarify the difference between Type B and Type A:
- CFexpress Type B CF4.0: These cards offer blazing-fast speeds, utilizing two PCIe lanes for a theoretical maximum of 4000MB/s data bandwidth. They are the most common and widely supported format.
- CFexpress Type A CF4.0: Smaller size, Type A cards use a single PCIe lane, providing a maximum of 2000MB/s data bandwidth. While currently limited to a few cameras (such as the Sony A7 IV, A1, and A7S III), they are not as prevalent as Type B cards. However, their small size makes them a great choice for smaller cameras, although they are typically priced higher than CFexpress Type-B cards.
The New CFExpress 4.0 Cards
The landscape has shifted with the advent of USB 4.0 and CFexpress 4.0. Here are some key points about the latest CFexpress 4.0 cards:
- Performance: CFexpress 4.0 cards far exceed the write speeds that the current cameras require.
CFexpress Type-A is capable of 2000MB/s
CFexpress Type-B is capable of 4000MB/s
CFexpress Type-C is capable of 8000MB/s - Compatibility: Older cards benefit from increased bandwidth when connected to USB 4.0 readers and cables, but the real game-changer lies in future-proofing. These cards ensure you’re ready for upcoming camera models with PCIe Gen 4 hardware. You will, however, need a camera and computer with this latest hardware to take advantage of this performance.
CFExpress Type-B CF4.0 BenchMarks
I have many new CF4.0 cards and have started running benchmarks to see if their performance gains are worth it.
For these benchmarks, I’m using the AJA System Test on a Windows 11 machine with a USB4.0 motherboard and the Prograde CF4.0 readers.
| Memory Cards | Write Speeds | Read Speeds | Sustain Speeds |
| ProGrade Gold 256GB/512GB CF4.0 | 1470 MB/s | 2713 MB/s | 822 MB/s |
| Delkin Black 325/650GB CF4.0 | 1498 MB/s | 2202 MB/s | 1501 MB/s |
| OWC Atlas Pro CF4.0 256/512GB | 1377 MB/s | 2667 MB/s | 762 MB/s |
A Few Issues I was Having With This USB 4.0
You may have noticed that the CFexpress Type-B cards are not hitting anywhere near their rated USB 4.0 Write Speeds in the above benchmarks.
I had a few issues with my computer and the Prograde CF4.0 Type-B reader that I’m still working out. If I use the CFexpress USB 4.0 reader on the CFexpress Type-B cards, I only hit speeds of around 700MB/s. I have to change to a USB 3.2 2×2 port to get the write speeds you see here. I’m unsure if it’s an issue with my computer or a defective reader. I use the Asrock z790 Motherboard, which has all the USB4.0 features enabled in the bios. Eventually, I’ll probably update my Macbook Pro for USB4.0, which may solve the problem, or try another reader from another brand.
Be sure to double-check the Prograde reader to see if you have a new PC build, and let me know if you have the same issues as I do. I don’t want to blindly replace my reader if it’s not confirmed defective since they are expensive.
CFExpress Type-A CF4.0 Benchmarks
| Memory Cards | Write Speeds | Read Speeds | Sustain Speeds |
| ProGrade Iridium 480-960GB | 1272 MB/s | 1532 MB/s | 687 MB/s |
| OWC Atlas Pro 480/960GB | 1275 MB/s | 1535 MB/s | 692 MB/s |
With the Prograde CFexpress Type-A USB4.0 reader, I am getting decent speeds, although nowhere near the rated speeds yet. This could potentially be solved with a better cable or a new motherboard. This tech is new, so there is still much to work out.
Is It Worth It?
Absolutely! If you’re in the market for a new CFexpress Card and the price isn’t out of reach, grab one of the new CF4.0 cards. If you prioritize performance and want a card that will keep you future-proofed, CFexpress 4.0 is the way to go. While they come at a slightly higher price, the investment pays off in speed, reliability, and compatibility with upcoming camera technology.
Remember, CFexpress 4.0 is an investment that should last you a while, as I can’t imagine needing more than 2,000 MB/s from a camera any time soon.
There is one caveat. If you’re a videographer or cinematographer, you should still prioritize a card with a high sustain speed over CF4.0 burst read and write speeds. Sustain speeds are limited by the type of flash used, not by the interface and memory controller. As you can see from the benchmarks above, the Delkin CFexpress Type-B card shows almost double the sustained speed compared to the OWC and Prograde cards. In this use case, I would even grab a CF2.0 card over a CF4.0 card if it has a higher sustain speed.
These links will take you to all the CFexpress Type-A and CFexpress Type-B benchmarks to compare.
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Dear Alik,
I am changing from nikon DSLR to the Z8 and was looking to buy a new CF card. I initially wanted to go for the Lexar Gold 512Gb (price&size vs sustainable write speed).
I then however found out OWC Atlas Pro 512Gb and they claim to have read and write speeds of 3000-3500mb/s. So with future proofing in mind, I ordered the OWC.
But in your review it seems that OWC are not capable of (nearly) reaching that and the sustained write speed is about half of that of the Lexar Gold series (1300mb/s). Is this the write&read speed through your computer (seems so?) and should I also assume that in my Z8, this will also only be around 700mb/s? Because that would almost half the 20fps rate when shooting RAW. As both the camera and the card still need to be shipped, I cannot test this myself (yet).
thanks in advance,
Tom
Yes, the sustain speeds are tested on a computer.
You can compare all the CFexpress Type-B cards here: https://alikgriffin.com/best-cfexpress-type-b-memory-cards/
I’ve tested most of the CFexpress Type-B cards in the Nikon Z8 as well just not these latest OWC cards yet. You can see that here: https://alikgriffin.com/best-memory-cards-nikon-z8/
The camera seems to top out at speeds of around 720MB/s as it only uses the single lane of the CF2.0 interface. However, testing it on a computer will use both lanes, giving double the speeds.
Theoretically, our cameras could double their speed by using both lanes with the CF2.0 interface before even needing to upgrade to the CF4.0 interface.
But regardless of whether you use the OWC CF4.0 or Lexar CF2.0, you’ll only be able to pull about 700MB/s out of the camera when processing photos. I wouldn’t expect the Nikon Z8 II to do better than this either, as they don’t need to make these cameras faster yet. The Canon R5 only did around 400MB/s max, and we’re only now seeing the upgrade with the R5 II to the faster capabilities of these CF2.0 cards.
So, I’m guessing it will be years before we see cameras really pushing speeds faster to meet the demands of CF4.0. Right now, CF4.0 is mainly only useful for copying offloading footage (it is very nice for backing up everything on film sets or in studio shoots when not tethered).
The sustained speed is still going to be an important factor when it comes to recording video, and that’s limited more by the type of slower flash used rather than the CF interface.
Memory cards use two types of flash: an SLC flash that works as a buffer and a slower flash, like an MLC or QLC, that the SLC flash dumps to or during longer write cycles.
It looks like OWC looked at how cameras are using cards ( using only the single lane of the CF2.0, which maxes out at speeds around 700MB/s-800MB/s ), and they only used the MLC flash to meet those demands and to save on costs.
Also, these cards use thermal components that might only have a life of around 5-8 before hardening, so you will lose some cooling efficiency after that, which could potentially affect performance.
As of right now, it won’t really matter which card you go with, OWC or Lexar, as this generation and probably the next generation of cameras will likely not hit the cards faster than around 700MB/s-800MB/s.
But you never know, Nikon could upgrade to the CF4.0 interface on the next models of cameras, and it would give you insane burst buffer performance with these OWC cards.
For now, the advantage of the OWC cards will come from using USB4.0 readers for insanely fast copy speeds, if you have a USB4.0 computer. However, if you’re copying a ton of data, you will be limited by the sustained speed of the drive you are copying to and, eventually, the sustained read speed of the OWC card, which I don’t test.
Hope that helps.