Hi,  How much memory does it show in the BIOS? It should work in optimizer mode. If you switch to advanced ECC mode it will add extra memory error correction(SDDC). What version is the BIOS at?
my dell poweredge t620 has 32g memory with samsung 4 x 8gb ( 8GB 2Rx4 PC3L-10600R) in slot (a1, a2, b1, b2) I hope to update the memory to 64G,and bought kingstone 4x8gb ( 8GB 2Rx8 PC3L-12800R). i've tried plug the kingstone in (a3,a4,b3,b4), and the bios detected 64gb ok，but the system displayed 64gb with only 32gb aviable. i)  anyone tell me how to mix them ? and the bios setting should be changed from optimized to addvance ecc OR not? ii) the manual shows that  (8gb 2rx4)  can be used for 64gb instead of  (8gb 2rx8) , if i got 8x8gb ( 8GB 2Rx8 PC3L-12800R)  for memory update is ok?
how to Mixing 2Rx4 and 2Rx8 ddr3 for t620