Hi just got a seagate 5tb expansion hdd, connected it to my imac late 2013, checked if both hdd's, (the new and the other seagate 4tb backup plus) are at 5gbps speed. all ok! started copying the 4tb files from old hd to the new. for about 30min speed was ok, then it slowed at below 480mbps, tried blackmagic speed test and it goes at around 10mbyte ps. checked the speed from utility and its still 5gbps but the problem is that it consumes only 8mA current while the other hd requires 144. usb bus dont get enough current. how to fix it???