I tried to search some information on this; but unfortunately could not find anything. Could someone help me understand if it is possible to use XQD card in a Nikon D810.
According to the manual the D810 has one SD slot and one CF slot. XQD cards are not on the list of tested and approved cards.
XQD is a media card format that was designed to be a successor to the CompactFlash card. XQD has been adopted by Nikon and was first incorporated into the D4 and D4S and subsequently into the D5 and D500 DSLRs.