Glad you found a solution.
I was being cagey because you never know the real situation with a forum post and messing with power can start fires.
Do remember that the dcdc is going to dissipate heat proportional to its load. So check that it doesn't get too hot during heavy use. 5v rail doesn't usually run much but USB , SATA, some logic ic's, and potentially the RAM, could all be running off the 5v