text: can a 512mb rdram (ecc) go hand in hand with a non ecc? i have system which supports rdram and i wanted to upgrade the memory.i unknowingly bought a single slot 512mb rdram (ecc) (pc800-40ns).i then realised i needed to buy them in pairs.can i get another 512mb (ecc or non ecc) 45ns to make them a pair ? you can not mix ecc with nonecc. however you can get another 512mb ecc rdram to go with the 512mb ecc rdram you already have. but you should make sure the system even supports ecc before you buy the other pair. also check and see if the system can support up to 1024mb of ram because you might have to go lower.