Unfortunately, we do not have a tested graphics card list that we can share with you. Generally, as long as the PCI Express* card complies with the PCI Express* Technology, it should work; for further details on this technology, please, refer to the following URL:
You could also double-check with the video card manufacturer to see if they have a desktop board compatibility list of their own.
I do notice the Intel(R) Desktop Board D915GAV provide support for PCI Express Revision 1.0a (Click here) while the Intel(R) Desktop Board DP43BFL does for 1.1 (Click here). Is your testing video cards 1.0a or 1.1.?