I have a MP4,1 flashed to 5,1 (W3690), currently with 16GB (4x8GB) of DDR3 ECC 1333MHz modules. 16GB was a decent whack way back when I stuck that in but obv not so much now, so I'm looking at swapping out 2x4GB modules for 2x8GB. I did a search for "DDR3 ECC 1333MHz 240pin" but there still seems to be things I don't quite follow. The vagaries of UDIMM, RDIMM, ECC, non-ECC etc are beyond me. I can see what I reckon must be compatible here, but I'm also not sure about the effects of mixing modules. For example, I think I cannot mix ECC and non-ECC, but I'm not sure. Can somebody give me a quick summary of what I can and can't do?