Just tested both with QuickBench 4.04. Large 1TB Sequential Custom Test (average of 5 iterations): 1TB = 208MB/s READ, 207MB/s WRITE 3TB = 174MB/s READ, 173MB/s WRITE Also faster on small random writes: 1TB = 57MB/s 3TB = 38MB/s Tested two 3TB in case it was a dud. No dud. Just slower. Not a huge deal but just thought you would like to know. P.S. Those are not Fusion Drives -- just the regular HDDs.