PCI Express (PCIe) Explained

PCIe – Some may know what it stands for, but most do not. Short for Peripheral Component Interconnect Express, PCIe is a high-speed serial computer expansion bus standard that has been around for years and is commonly used in PC graphics cards, hard drives, SSDs, Wi-Fi and Ethernet hardware connections. It is only more recently that PCIe technology has begun to be utilized in memory storage devices geared toward both the professional photo and video markets, such as Delkin’s CFexpress Type B memory cards and JUGGLER™ USB 3.2 external SSD. You may be wondering, “What’s the big deal?” or “How is it different from other memory cards?” Here, we break down how PCIe technology differentiates itself from the rest and the new opportunities it brings.
In comparison to other bus standards, PCIe allows for significantly better performance – PCIe 3.0 with 16 lanes can offer transfer speeds theoretically up to 15.75 GB/s. Storage media, like CFexpress Type B memory cards, use four PCIe 3.0 lanes where each lane can provide 1 GB/s of data. Read and write speeds for a Delkin 1TB CFexpress Type B memory card can reach up to 1730MB/s and 1430MB/s respectively, while a 1TB JUGGLER™ USB 3.2 external SSD offers both read and write speeds up to 1700MB/s. At these incredibly fast speeds, high-end hosts that are used in today’s broadcast, cinema and photography industries are capable of capturing flawless cinema-quality video, including 8K, 6K & 4K at high frame rates and bitrates, as well as RAW continuous-burst photos. Quick, efficient offloading is also guaranteed as users are able to gain immediate access to their files and start post-production sooner. This is ideal for photographers and videographers who need to quickly unload large amounts of data and get back to shooting.
Speeds of this magnitude have never before been available in storage media specifically designed for the photo and video market, but unfortunately there is a small trade-off. PCIe-based products tend to generate a large amount of heat, which in excess can be harmful to the media, camera, and even the user. This explains why computers utilize fans and cooling systems to regulate the machine’s internal temperature. In order to ensure protection for all involved, the controller used employs an on-die thermal sensor and multiple throttling states to keep its temperature below 90°C (194°F) during usage. When the controller temperature exceeds 88°C (190.4°F), the controller starts the thermal throttling process and 1st throttling state (“Light Delay”) is triggered during which performance speed is reduced by 30%. If the temperature hits 90°C, the controller will go into the 2nd throttling state (“Heavy Delay + Frequency Reduction”), reducing original performance speed by 50%. Thermal throttling states will be triggered as long as the controller’s temperature range is within 86 – 90°C. Once it reaches 86°C (186.8°F), the card (or drive) will either return to the previous throttling state or leave the thermal control mechanism and re-apply the full speed performance.

Now, you may be wondering how long it will take for your card (or drive) to reach that temperature range, but unfortunately there isn’t a straightforward answer. Various factors can contribute to how quickly that may happen, including outside ambient temperature, host, mode, and operation time. For example, a CFexpress memory card used in a Canon 1DX Mark III that is continuously recording 5.5K 60fps 12-bit RAW video at 2600 Mb/s will most likely last longer in a cooler environment than somewhere hotter. In comparison to CFexpress cards, external SSDs (e.g. Delkin USB 3.2 JUGGLER™) will experience the heat issues differently as they are used outside of the camera, but also due to how each is designed and what materials and components are used.
To make sure everything you intended to capture is safely stored without corruption or dropped frames, we recommend having at least one additional card (or drive) on-hand. Check the heat of the storage from time-to-time by using your hand, and if it is too hot to handle, swap it out with a “fresh” unused unit so that the one that was just used can cool down – ideally someplace cool and dry. Going back-and-forth between cards (or drives) to give each “rest” will ensure peak performance and increase longevity.
Performing a full-format on your product regularly is also recommended as it will completely remove any data lingering from a previous recording, which can possibly cause issues in the middle of shooting. Despite if a quick format was done, data from old files remain and that buildup can slow down the sustained write speed of the card (or drive), forcing the camera to stop its current activity. This tends to occur more when recording continuously in demanding video modes, such as 4K at high frame rates and bitrates. To guarantee maximum video recording performance, full format regularly and after extensive use.
Specific only to PCIe-based external solid-state drives, it is important to use either the USB cable that came with the product or only high-speed rated cables. Not all USB cables are built and designed the same, so even though a cable off eBay may cost less, it may limit advertised speeds and what your camera can do. The cables included with Delkin’s JUGGLER™ USB 3.2 SSD (USB Type C-to-C and USB Type C-to-A) have been tested extensively in order to guarantee speeds as advertised.
Despite the slight heating issue, the benefits PCIe-based products provide far outweigh the side effects. The technology offers the fastest available speeds on the market, opening up new, exciting possibilities for photographers and videographers of any skill range.


Newest, latest technology with room to grow Requires purchase of a new card / drive for use
in supported hosts
Fastest available speeds on the market (up to
16 GB/s in the future)
Usage could generate significant heat (media may
need to be swapped out during a long shoot)
Capture flawless cinema-quality video, including
8K, 6K & 4K at high frame rates and bitrates
Throttle feature may slow down the card / drive
if the temperature exceeds safe levels
External PCIe is incredibly fast when used with
the proper cable
Cheap or poorly made cables can limit possible
read and write speeds
Periodic Full-formatting will keep the card or
drive fast and fully functional
Full-formatting requires extensive time to
completely perform