Yes, you can run these together. Just start with 2.1Vdimm and 5-5-5 timings prior to booting with both installed. After booting, you can try tighter timings/faster memory bus to see what the MB/memory combination will handle. Always test with memtest86 (memtest86.com free download) to verify the new settings are stable, prior to booting into the OS.
Always backup your data, prior to changing settings in the BIOS.