Just in case someone reads this and decides to try it: Make sure to connect the ground net (GND, usually but not always a black cable) from external power supply to one or more ground pins in the SATA power connectors - Otherwise, in case of different output ground potentials (since the external PSU and Odyssey DC/DC parts are floating relative each other), all potential-equalizing currents will go through the SATA HDD data connector, which might disrupt the data transfer.