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Eye-Fi cards' write speed comparison


I have never paid much attention to SD cards' write speeds as they have always been fast enough for me. Today, however, I tried recording HD video with my new Canon S100 and my old Eye-Fi Explorer card and the camera shut down the recording after 40 seconds. The camera buffer had filled up and the card was not writing the data fast enough.

I know the newest "Pro X2" is advertised as a "Class 6" card and both the "Pro" and "Pro X2" are handling HD video without problems in two other cameras, but I had no idea how much faster the "Pro X2" is compared to the old cards. With four cameras in the house and four Eye-Fi cards I did not want to buy a fifth card without having some hard facts to base my purchasing decision on.

Well, that might not be entirely true, but since I could get some hard evidence before buying, I decided to do a test.

Write speeds for the different Eye-Fi cards:

  • Classic: 1.8 MB/s
  • Explorer: 1.8 MB/s
  • Pro: 4.2 MB/s
  • Pro X2: 12.2 MB/s

The test was done with the OSX application "Blackmagic Disk Speed Test" on an iMac using the built in SD card reader. I used a 1GB test file as that is the smallest file this application can use for testing.

Read speeds are not as important and the results where all over the chart:

Read speeds for the different Eye-Fi cards:

  • Classic: 14.0 MB/s
  • Explorer: 12.5 MB/s
  • Pro: 18.7 MB/s
  • Pro X2: 15.5 MB/s

All in all, the original Eye-Fi cards are slow and the old Pro card is not very fast either. Looks like I am going to have to get myself one more Pro X2 card after all.

you're right

Submitted by Ziv (not verified) on Mon, 09/03/2012 - 09:21


Your #'s are correct :-) The X2 cards have our X2 chip inside, which includes our own controller, and are in fact faster then Class 6. Class 6 cards require write speeds for 8MBps, and as you've outlined, our X2 cards (any X2 card) can sustain 12MBps writes, which is faster then Class 6. We're not fast enough to claim Class 10, and there is no Class 8, so we conservatively mentioned Class 6.

Here is a tip -- when performing speed tests on our cards, turn off the Eye-Fi Helper, BEFORE inserting the card into the reader. The Helper detects the card, and the firmware that's on the X2 card puts it in low-power mode, so that it would work in more (poorly designed) card readers. So if you want the card to work in full power and full performance mode, just don't have the Helper running.

But anyway, your write speeds are correct, so it seems like you either didn't have the Helper on, or the card didn't need to go into low power mode.

Here is another tip -- QuickBench is also a great performance app, and is the one that Rob Galbraith used for all of his tests.

Thx --


Eye-Fi co-founder

Faster than Class 6

Submitted by dumell on Tue, 09/04/2012 - 08:52

I was thinking that my results where clearly above Class 6 for the Pro X2, almost Class 10. Thank you for insights and suggestions.

Regarding the Helper software; it was not on in the computer I used for the tests but that was a pure coincidence as I did not know about the low power mode.