Check your riser SATA cable!

use ver 006C riser, SATA to Molex cable yellow cable melted....
just found it is NOT suggested to use SATA to supply power to riser as it should be overload....
should use PCIE to supply power to riser...
for high grade GPU, SATA power source is not enough.....
and if cable with no mark, those cable should NOT use.
must use those cabled marked 18AWG... if cable on those converter with no mark, don't use those molex converter....

just learn a lesson, lucky just the cable melted only, after changed to PCIE as power supply instead of SATA, not problem now.

good luck.