Mate 4 sticks will work - and if you want to get the benefit of dual channel memory as supported by your motherboard then you will need to find 2 x 32GB Ram sticks. I do know that there is ECC rated ram in 32GB size modules.
Real world difference between dual channel and not is un-noticeable. The amount of RAM is however a very big plus.
Quick question are you planning on using his as a server for critical operational or data purposes? If yes the ECC ram run at stock would be my advice.
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