Yes, you can.   Place the 8gb DIMM's in slots A3,A6, B3, B6 and set the memory mode in the F2 bios to memory optimized.   This should work with no errors.   Regards,
We have a PowerEdge R610 with dual processors with 8x 4GB DIMMs (and with 4 slots free).  Can we safely add 4x 8GB DIMMs, bringing our total memory up to 64GB? Are there any issues with this upgrade?
PowerEdge R610 Memory Upgrade