The D800 Users Manual lists Sandisk Extreme Pro 64GB and 128GB CF cards as Tested and Approved. The Lexar 1000X CF cards were not tested, though I suspect that they will work without issues. The D800 approved SD cards are listed up to 64GB. The Lexar 128GB SD card is SDXC compliant so I suspect it will work as well. Good Luck and Enjoy your Nikons!