hello all and thank you for your time. I have an HP Phoenix H9-1350 with a 600w OEM PSU. I currently run an XFX DD HD 7870 just fine. I was wondering if I can upgrade to an XFX R9 280/280x with this PSU...PC specs: http://h10025.www1.hp.com/ewfrf/wc/document?docname=c03518194&cc=us&dlc=en&lc=en...