again, you want to use the identical RAM to the 3 modules you already have in there. thus, find out what exact brand/model you have, then buy the same thing.
if you can't source the identical brand/model for some reasons, at least you need to match the same type. non-ECC to match non-ECC, ECC UDIMM to match ECC UDIMM, ECC reg to match ECC reg. I do know it for a fact that you can't mix non-ECC or ECC UDIMM with ECC RDIMM on one server board.
Wouldn't it be easier to just buy RAM for the entire thing all at once and either use the "old" RAM for another server or sell it off to make some money back?
At least, that's how I'd do it, if given the circumstances.
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