Repair Windows Installation

Hey, My PC multiboot = Linux, Win XP, Win 8.1; Bootloader = GRUB2 Recently the motherboard gave in; replaced it without issues for Linux and win 8.1, but on Win XP I had no keyboard or mouse. Also, in Win XP I only booted once in normal mode, tried then all the other safe modes, etc -...

I have a i5-2500k sandy bridge CPU 8GB-DDR3 RAM a GT 9500 GPU(really outdated) Mobo is a ASUS P8Z77-M and a 500W PSU And I was wandering if my PSU can handle a gtx 1080 or would I have to upgrade it too.