Both processors must match stepping and revision and part number. No such thing as 2633 ram  Must be Registered ECC 2666 Ram [URL] MTA18ASF2G72PDZ-2G6J1 DDR4-2666MT/s • 16GB Module Capacity   RDIMM • 2 Rank x 8  PC4-21333 • CL=19 • 1.2V • ECC  Just like the processors the Rank Speed, Vendor must all match and ram is paired. So if you have 2 modules for CPU1 you must have 2 matching Modules for CPU 2 and so on. The side panel inside the cover usually has a picture of the ram configuration.
I have a Dell Precision 7810 XCTO with Single E5 2630 v3 Xeon pr9cessor, 32 GB ECC 2133 hz RAM (8GBx4).  Now i want daul processor and 64GB RAM.   My questions arr as 1. Can i use a different processor or not? 2. Can i use 2633Hz additional RAM or should i changed all.
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