You can refer "System Memory" section on Page 100 of below link for more details on memory configuration for R810. The link also have sample memory configurations. As you have sixteen 16GB modules you can insert it on "A1,A2,A3,A4,B1,B2,B3,B4,C1,C2,C3,C4,D1,D2,D3,D4" slots [URL] 
Hi all,First time server owner here so please forgive me if this question is blazingly obvious to the average user. My Poweredge R810 came with all 32 slots filled with 4GB sticks. It has 4 cpu's. I purchased 8x 16GB sticks but had issues installing and getting it recognised, then when it was recognised the bootup told me it was not optimal and I definitely noticed the server itself was very sluggish. Is it not advisable to mix 16/4's? I have ordered another 8x16GB which will give me 16x16. What is the best thing to do in this scenario? I am limited by cost and availablility in Australia right now. Thanks for any suggestions in advance 
R810 Memory Configuration help please