EOS-1D X Mark II not using memory card's full capacity

[Sportseditor123]

I just got a used 1DX Mark II.

I've got a 64GB SanDisk CFast 2.0 Extreme PRO memory card and a SanDisk Extreme 128 GB compact flash card.

The camera switched storing photos from the CFast card to the SD card after 3.67 GB on the CFast card.

I wasn't notified that it switched and I'm perplexed why it did that when there was plenty of storage left.
I shoot RAW.

Thank you for any help.

[deebatman316]

Let me ping @Rodger he is a 1D series camera user.

[shadowsports]

Greetings 

The 1DX Mark II formats CF Express cards using exfat.  A 4 GB card will yield a formatted capacity of approximately 3.72 GB.  A small portion of this is reserved for the file system, hence why you see 3.67 GB available.  😉

[Sportseditor123]

I've got 64 GB card.

[Peter]

1D X II with certain SanDisk cards had an issue until 1D X II was updated to 1.0.2. 

Though the symptom was different.

"If a SanDisk CFast card is inserted into the camera or a card reader, the bottom part of still images recorded may be corrupted.
This phenomenon is confirmed in images recorded in both the RAW and JPEG formats.
In the RAW file, the image corruption may appear in the bottom right corner of the image.
In the JPEG file, the image corruption may appear in the lower third area of the image.”

Affected cards.

SanDisk Extreme PRO CFast2.0 64GB (SDCFSP-064G-xxx)
SanDisk Extreme PRO CFast2.0 128GB (SDCFSP-128G-xxx)
SanDisk Extreme PRO CFast2.0 64GB (SDCFSP-064G-xxxA)
SanDisk Extreme PRO CFast2.0 128GB (SDCFSP-128G-xxxA)
SanDisk Extreme PRO CFast2.0 64GB (SDCFSP-064G-xxxB)
SanDisk Extreme PRO CFast2.0 128GB (SDCFSP-128G-xxxB)

[Waddizzle]

Did you open the card slot door, at all?

Is this your first experience with a camera body with dual card slots?

[shadowsports]

Greetings,

Thank you for clarifying. I missed the 64 GB In your comment.  I've not seen the destination media change just by opening the door.  It happens when one of the cards is physically ejected and the door is closed.  I often open the door eject my CF Express B card extract images and video using a card reader then return it to the body without closing the door.  I did do it once years ago and ended up with everything on my SD card.  I was very concerned for about 3 seconds 🤣. 

@Peter This is helpful information I've not read up much on the 1DX Mark II 👍

@sportseditor123, By chance was this card formatted outside of the camera?  What does its formatted capacity appear as?

[Waddizzle]

Thanks, Rick. I forgot to point that out. The phone rang and I got distracted.

There’s more to it than opening the door to the card compartment.  You have to remove a card and then close the door.  This may cause the camera to switch to the other card, if the card you removed was the primary card to save photos. 

[Sportseditor123]

Did not open door.

Yup, upgraded from a 7D.

[Sportseditor123]

I didn't open the card door compartment.