I advise people to follow the guideline that if the power supply does not have the proper GPU connector it was not actually designed to support that level of gpu.
There is no requirement for a 600w psu to output 600w to be able to put a 600w sticker on it.
Would not trust a $200 GPU to that PSU, let alone a $350 one.
General rule of thumb, never go cheap on the part that can destroy all the other parts.