Hi, 

I have an R520 with 4 x 16GB DDR3 1600 MHz DIMMs and I am looking to add in another 4 of the same size and speed, with part number JDF1M.  

I was expecting slots A1,B1,A2,B2 to be populated, but it is A2,B2,A3,B3.  

Is it OK for me to add the new DIMMs in to A1,B1 and then A4 and B4 ?  Just wanted to double check in case this had any specific configuration required.