I have a 600w power supply hooked up to a GTX 770 from gigabyte. I want to trade it om a r9 280x vapor x edition from saphire theo only problem is the specs for the 770 says it uses 6-Pin / 8-Pin ad the r9 says it uses 8-PIN to 4 PIN x2. Would I be able to use the same power cable from my PSU for the vapor x?