Swapping Perc 6/i with Perc 6/iR in Dell R710, invalid PCI card error

Solution 1:

When you say "PERC 6/iR", are you referring to the SAS 6/iR card? If so, that should be completely compatible with your system... Try double-checking you have the correct part number though (YK838), and make certain that it's a SAS 6/iR, preferably one that was originally shipped in the same server "generation" or a server model that shipped w/ this same part (The same form factor of this card is used in the R710/610/510/900, similar tower models, and even the 1900 and 2900 series - uncertain if other revisions/version exist)

As others suggested, a BIOS update would also be a good first step, combined w/ the latest firmware (go with latest Dell firmware for best chances of compatibility).

Many people who run into this issue and report it to Dell end up having purchased an incorrect part, so try to be double-sure you have the right one... perhaps consider getting another on eBay, if even just to test with? Looks like they're plentiful and affordable there.