My PSU (Corsair CX650) has 3x 6 pin headers and 2x 8 pin headers, and came with 2x cables with 8 pins on one end and 6+2 on the other. My video card (Gigabyte GTX 760) has an 8-pin header and a 6-pin header. This works fine for connecting the 8-pin header on the video card. However, when it comes to connecting it's 6-pin header, these cables do not work, as I have no way to connect 6-pin to 6-pin. My question is, would it be ok to use the other cable to connect the GPU's 6-pin header to the PSU's 8-pin header? I ask this because the GPU came with molex adapters, but I've heard these are highly unpreferrable.
EDIT: Think I found the answer in related threads (apparently it is ok), but just to be safe I wanna leave this open.