Will server just not recognize memory sticks or downgrade to max supported speed of 2400 MT/s? Memory sticks I had in mind are from my desktop that can run at 2800 MT/s DDR4.
I am waiting for server to arrive to test myself but I’d figure someone might know the answer before I find out for myself.
Yes and no, an R630 is only able to run RDIMM and LRDIMM at 1866, 2133, and 2400 MT/s, due to the generation of processor it supports. Anything higher than 2400 MT/s will be just be stepped down to the next speed. You are better off buying the maximum supported configuration rather than buying something out of spec.