Sonnet SF3 CFexpressB/XQD Pro Thunderbolt 3 Card Reader – All that Speed!


Things have been a bit disappointing as of late. The fastest external data transfer rate for media is Thunderbolt 3 and, well, the industry just doesn’t want to keep up so it seems.  Thunderbolt 3 has been around for some time, but good luck finding it integrated directly into motherboards but for that of ASRock, unless of course you want to spend much more for a specific motherboard and matching Thunderbolt 3 card for that board. intel xeon e5

Once you do have such a board, as with our  Test Bench with dual Tbt3 ports shown , there are plenty of portable SSDs but good luck finding a Tbt 3 card reader. There are three. In all reality, the need at the consumer/enthusiast level just wasn’t there until most recently, with Canon’s latest release of the EOS R5 mirrorless camera. The R5 can hit 20FPS, has 8K video and is the first enthusiast level camera in the industry to have a CFexpress Type B card integrated.  Worldwide sales of the R5 to date have been unparalleled…and CFexpress cards are suddenly appearing en masse.  The R5 is a game changer.

The key to CFexpress is its data transfer rates reaching as high as 1800MB/s and the only way to reach these speeds is through Thunderbolt 3, capable of reading and writing external data transfer up to 2.8GB/s.  The problem is price as can be seen with all but three CFexpress card readers available today. Manufacturers sacrifice speed for value and market USB 3.2 CFexpress Type B readers that achieve a top speed of 1GB/s at PCIe 3.0 single lane.  Since you are reading from the card and writing to your PC, you are losing almost 80% of the speed that your CFexpress card is capable of.  The Sonnet SF3 CFexpress/XQD Pro Thunderbolt 3 Card Reader changes all of that.

SF3 packaging contains the SF3 itself, a power adapter, a Quick Start guide, Thunderbolt 3 cable and a Thunderlock 3 connector that screws into the back of the unit to hold your cable securely in place.

The Sonnet SF3 CFexpress/XQD Pro Thunderbolt 3 Card Reader is a solid brushed aluminum and contains two ports for at the front.  Both are capable of reading and writing CFexpress or XQD simultaneously.

Very impressive is the fact that Sonnet Technology has included dual Thunderbolt 3 Type-C ports in the back, as Thunderbolt 3 can be daisy chained to other Type-C devices.

As can be seen in this photo above, The exterior construction is a ribbed aluminum which serves as a heatsink for the device as continuous data transfer speeds up to 1800MB/s can get hot.  A quick look at the Crystal DiskInfo result for the SanDisk  Extreme Pro validates that we are moving data at PCIe 3.0 x2 (2 lane) speeds.

As one might expect, pricing for Thunderbolt 3 card readers are significantly higher than that of USB 3.2 Type-C, and even more so for a reader with the build of the Sonnet SF3 CFexpress B/XQD Pro Thunderbolt 3 Card Reader.    It can also be purchased from  for $199.

So let’s take a look at data transfer speeds on the next page…