I hate intermittent problems!!!! My D4 comes up with a "card err" problem every so-often. XQD is primary, CF is backup. If I format the cards in the camera or on the computer, the problem goes away for a few shots, then it comes back. If I use only one card (either card) the problem seems to go away (I have not tried this for a long shoot.)
My XQD is Sony's G series (400 MB/s). Anyone else seen this problem?
Robert M. Poston: D4, D810, V3, 14-24 F2.8, 24-70 f2.8, 70-200 f2.8, 80-400, 105 macro.