I bought a used Sapphire r9 280x dual x on eBay (I know all the risks I took) , my issue is the computer won't boot after powered off completely, but will boot if you hit the reset button after it doesn't boot, and it works fine. I didn't have this problem with my old card I replaced which was a evga gtx 640. I've tried all troubleshooting I can think of reseating, cleaning connectors, reset cmos, all drivers from old card were uninstalled. My system is brand new otherwise i7 4790k, asus z97 a, psu is evga supernovae g2 750w. I'm stumped.